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Source: Forensic Science International 137 (2003) 152-159<br>
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Source: <i>Forensic Science International</i><br> 137 (2003) 152-159
 
  
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=<font color=orange>Distinction of bloodstain patterns from fly artifacts</font>=
  
<h1><font color=orange>Distinction of bloodstain patterns from fly artifacts</font></h1>
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[More [[All Mark Benecke Publications|articles from MB]]] [Articles [http://wiki2.benecke.com/index.php?title=Media#Interviews_.26_Articles <font color=lightgrey>about MB</font>]]<br>
  
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'''BY MARK BENECKE <sup>1</sup>* and LARRY BARKSDALE <sup>2</sup>'''<br>
[Weitere [[All Mark Benecke Publications|Beiträge und Interviews]]]
 
<html><br>
 
  
Mark Benecke (1)*, Larry Barksdale (2)<br>
+
<i><sup>1</sup> International Forensic Research & Consulting, Postfach 250411, 50520 Cologne, Germany, E-mail forensic@benecke.com <br>
<br>
+
<sup>2</sup> Lincoln Police Department, 575 South 10th Street, Lincoln, Nebraska 68502, USA; lpd211@cjis.ci.lincoln.ne.us </i>
(1) International Forensic Resesarch &amp; Consulting, Postfach 250411,
 
50520 Cologne, Germany; forensic@benecke.com<br>
 
<br>
 
&nbsp;(2) Lincoln Police Department, 575 South 10th Street, Lincoln,
 
Nebraska 68502, USA; lpd211@cjis.ci.lincoln.ne.us<br>
 
<br>
 
 
*corresponding author<br>
 
*corresponding author<br>
  
<br><b>
+
 
Abstract/Summary<br></b>
+
<font color=orange>Abstract/Summary</font><br>
<div style="text-align: justify;"><br>
+
 
 
Forensic scientists may encounter blood spatter at a scene which may be
 
Forensic scientists may encounter blood spatter at a scene which may be
 
pure or a mixture of fly artifacts and human bloodstains. It is
 
pure or a mixture of fly artifacts and human bloodstains. It is
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advanced documentation of such stains since the mechanics of production
 
advanced documentation of such stains since the mechanics of production
 
of fly artifacts are not determinable to the crime scene
 
of fly artifacts are not determinable to the crime scene
reconstructionist from regular police forces. We describe three cases
+
reconstructionist from regular police forces.<br>
in which experiments and crime scene reconstruction led to additional
+
 
 +
 
 +
We describe three cases in which experiments and crime scene reconstruction led to additional
 
information. Case 1: Above the position of a victim, numerous blood
 
information. Case 1: Above the position of a victim, numerous blood
 
stains of the low-high velocity type were found. Exclusion of these
 
stains of the low-high velocity type were found. Exclusion of these
Line 45: Line 36:
 
submillimeter stains were found on a lamp between the two corpses.
 
submillimeter stains were found on a lamp between the two corpses.
 
Activity of flies was less likely compared to alternative scenario of
 
Activity of flies was less likely compared to alternative scenario of
moving lampshade and violent stabbing. <br>
+
moving lampshade and violent stabbing.<br>
<br>
+
 
<b>Key Words </b><br>
+
 
<br>
+
<font color=orange>Key Words</font><br>
Blow Flies, Forensic Entomology, Blood Stain Pattern Interpretation,
+
 
Blood Spatter Artifacts<br>
+
Blow Flies, Forensic Entomology, Blood Stain Pattern Interpretation, Blood Spatter Artifacts<br>
<br>
 
  
  
<b>1. Introduction</b><br>
+
<font color=orange>1. Introduction</font><br>
<br>
+
 
 
In the last years, forensic entomology [1-7] and blood stain pattern
 
In the last years, forensic entomology [1-7] and blood stain pattern
 
analysis [8-19] became more and more part of forensic investigations
 
analysis [8-19] became more and more part of forensic investigations
 
and trials [14] outside of the United States. &nbsp;<br>
 
and trials [14] outside of the United States. &nbsp;<br>
<br>
+
 
 +
 
 
In this context, crime scene experts often note that flies might leave
 
In this context, crime scene experts often note that flies might leave
 
information that could produce confusion within the scene. The
 
information that could produce confusion within the scene. The
Line 66: Line 57:
 
regurgitation and defecation from a fly are frequently not taken into
 
regurgitation and defecation from a fly are frequently not taken into
 
account. <br>
 
account. <br>
<br>
+
 
 +
 
 
Only old German texts [8] and modern text books from the United States
 
Only old German texts [8] and modern text books from the United States
 
mention artifacts produced by flies [16-19], e.g.: <br>
 
mention artifacts produced by flies [16-19], e.g.: <br>
<br>
+
 
 +
 
 
"The activity of flies at the scene where blood has been shed is
 
"The activity of flies at the scene where blood has been shed is
 
another possible source of small stains of blood that may be confused
 
another possible source of small stains of blood that may be confused
Line 79: Line 72:
 
surface to allow enzymes to break down the blood. At a later time, the
 
surface to allow enzymes to break down the blood. At a later time, the
 
flies return to the areas of regurgitated blood and consume a portion
 
flies return to the areas of regurgitated blood and consume a portion
of the blood. The surfaces upon which these activities have taken place
+
of the blood.<br>
 +
 
 +
 
 +
The surfaces upon which these activities have taken place
 
will contain small spots of blood material which are often a millimeter
 
will contain small spots of blood material which are often a millimeter
 
or less in diameter with no definite point of convergence or origin.
 
or less in diameter with no definite point of convergence or origin.
Line 88: Line 84:
 
locations may be inconsistent with blood spatter associated with
 
locations may be inconsistent with blood spatter associated with
 
injuries sustained by the victim." [19]<br>
 
injuries sustained by the victim." [19]<br>
<br>
+
 
 +
 
 
Although not true spatter, another pattern often confused with spatter
 
Although not true spatter, another pattern often confused with spatter
 
is the "fly speck" or "fly spot" pattern. Flies present within the
 
is the "fly speck" or "fly spot" pattern. Flies present within the
Line 96: Line 93:
 
examination.<br>
 
examination.<br>
  
<br>
+
 
 
In the case of regurgitation, the specks are remarkably
 
In the case of regurgitation, the specks are remarkably
 
symmetrical....Most often, the analyst finds these patterns in warm
 
symmetrical....Most often, the analyst finds these patterns in warm
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blood with a presumptive test. Obviously, care should be exercised in
 
blood with a presumptive test. Obviously, care should be exercised in
 
evaluating any abnormal patterns which meet these criteria." [10]<br>
 
evaluating any abnormal patterns which meet these criteria." [10]<br>
<br>
+
 
 +
 
 
However, no integrated approach by natural sciences and criminalists
 
However, no integrated approach by natural sciences and criminalists
 
had been used until actual case work (see cases below) and presentation
 
had been used until actual case work (see cases below) and presentation
Line 109: Line 107:
 
between blood spatter caused by force and blood spatter-like patterns
 
between blood spatter caused by force and blood spatter-like patterns
 
produced by flies.<br>
 
produced by flies.<br>
<br>
+
 
 +
 
 
This is expecially important since even artifacts caused by flies may
 
This is expecially important since even artifacts caused by flies may
 
very well include the vicitim&acute;s blood. Neither presumptive blood
 
very well include the vicitim&acute;s blood. Neither presumptive blood
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following text illustrates stains produced by the activity of flies and
 
following text illustrates stains produced by the activity of flies and
 
suggests methodology for evaluating stains in a decomposed body scene.<br>
 
suggests methodology for evaluating stains in a decomposed body scene.<br>
<br>
+
 
 +
 
 
Furthermore, from the above quotes it appears that some documentation
 
Furthermore, from the above quotes it appears that some documentation
 
of the crate was possible. In many countries, it is however unlikely
 
of the crate was possible. In many countries, it is however unlikely
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therefore, documentation of crates has, to our knowledge and does
 
therefore, documentation of crates has, to our knowledge and does
 
usually never take place. <br>
 
usually never take place. <br>
<br>
 
&nbsp;<br>
 
  
<b>2. Blood Spatter Types</b><br>
+
 
<br>
+
<font color=orange>2. Blood Spatter Types</font><br>
 +
 
 
Blood that is subjected to a low velocity impact (less than 1.5 m x
 
Blood that is subjected to a low velocity impact (less than 1.5 m x
 
s-1); resulting blood spots often around 4-8 mm in diameter) is called
 
s-1); resulting blood spots often around 4-8 mm in diameter) is called
 
low velocity blood spatter. It is caused by free-falling blood under
 
low velocity blood spatter. It is caused by free-falling blood under
 
the influence of gravity, including blood cast off from fist shoe, or
 
the influence of gravity, including blood cast off from fist shoe, or
weapon. <br>
+
weapon.<br>
 +
 
 +
 
 
Blood spatter as reported in the following three cases was usually
 
Blood spatter as reported in the following three cases was usually
 
thought to be caused be either high velocity impact, or by a mixture of
 
thought to be caused be either high velocity impact, or by a mixture of
Line 144: Line 145:
 
to a high velocity impact (&gt;7.5 m x s-1), e.g. a gunshot (blood
 
to a high velocity impact (&gt;7.5 m x s-1), e.g. a gunshot (blood
 
spots typically &lt; 1 mm in diameter) [9]. <br>
 
spots typically &lt; 1 mm in diameter) [9]. <br>
<br>
 
<b>3. Case I: Double homicide in Nebraska</b><br>
 
<br>
 
<b>3.1. General Scenario</b> <br>
 
  
<br>
+
 
 +
<font color=orange>3. Case I: Double homicide in Nebraska</font><br>
 +
 
 +
<font color=orange>3.1. General Scenario</font><br>
 +
 
 
The remains of two men were discovered at 14:25 hrs on 14. June 1997 in
 
The remains of two men were discovered at 14:25 hrs on 14. June 1997 in
 
in a third level apartment in a five-plex apartment building in urban
 
in a third level apartment in a five-plex apartment building in urban
 
Lincoln, Nebraska, USA [23]. <br>
 
Lincoln, Nebraska, USA [23]. <br>
<br>
+
 
 +
 
 
Both victims were fully clothed; both had a gunshot wound to the head
 
Both victims were fully clothed; both had a gunshot wound to the head
 
and gunshot wounds to the torso. One victim was found face down in the
 
and gunshot wounds to the torso. One victim was found face down in the
Line 159: Line 161:
 
carpeting. Pools of a reddish substance were observed around the bodies
 
carpeting. Pools of a reddish substance were observed around the bodies
 
of the victims.<br>
 
of the victims.<br>
<br>
+
 
 +
 
 
The bodies were in the active decay stage with black putrefaction only
 
The bodies were in the active decay stage with black putrefaction only
 
just beginning; the skin was intact everywhere except where there were
 
just beginning; the skin was intact everywhere except where there were
Line 166: Line 169:
 
well as some adult flies were present. The temperature registered 30
 
well as some adult flies were present. The temperature registered 30
 
&deg;C on the wall thermostat.<br>
 
&deg;C on the wall thermostat.<br>
<br>
+
 
<b>3.2. Forensic Entomology</b><br>
+
 
<br>
+
<font color=orange>3.2. Forensic Entomology</font><br>
 +
 
 
On 15. June 1997, at 06:45 hrs, the police collected six adult flies,
 
On 15. June 1997, at 06:45 hrs, the police collected six adult flies,
 
three third instar fly larvae and several hundred first instar fly
 
three third instar fly larvae and several hundred first instar fly
Line 178: Line 182:
 
that two distinctly separate periods of egg-laying by adult flies had
 
that two distinctly separate periods of egg-laying by adult flies had
 
taken place. <br>
 
taken place. <br>
<br>
 
  
<b>3.3. Blood Stains</b><br>
+
 
<br>
+
<font color=orange>3.3. Blood Stains</font><br>
 +
 
 
Initial observation of the scene gave the appearance of extensive low,
 
Initial observation of the scene gave the appearance of extensive low,
 
medium and high velocity blood spatters. Above the position of one of
 
medium and high velocity blood spatters. Above the position of one of
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and the walls around the victims. The stains were tested positive for
 
and the walls around the victims. The stains were tested positive for
 
blood with a quick test for hemoglobin (Hemastix/Heglostix)<br>
 
blood with a quick test for hemoglobin (Hemastix/Heglostix)<br>
<br>
+
 
 +
 
 
The first assumption to be made was that there had been slinging of a
 
The first assumption to be made was that there had been slinging of a
 
lot of blood around the kitchen and living room. This would suggest not
 
lot of blood around the kitchen and living room. This would suggest not
Line 201: Line 206:
 
bathroom of an assaultive nature and the bloodshed had taken place in
 
bathroom of an assaultive nature and the bloodshed had taken place in
 
the kitchen and living room.<br>
 
the kitchen and living room.<br>
<br>
+
 
 +
 
 
Recostructing the angle of impact of many of those stains, however, led
 
Recostructing the angle of impact of many of those stains, however, led
 
nowhere. There was no indication that the bodies had been moved and
 
nowhere. There was no indication that the bodies had been moved and
Line 212: Line 218:
 
(b) transferred to the walls? <br>
 
(b) transferred to the walls? <br>
  
<br>
+
 
<b>3.4. Experiments and Measurements at the Scene of Crime</b><br>
+
<font color=orange>3.4. Experiments and Measurements at the Scene of Crime</font><br>
<br>
+
 
 
It is known that after feeding, flies regurgitate and defecate. Hence,
 
It is known that after feeding, flies regurgitate and defecate. Hence,
 
flies could have caused stains, containing blood of the victims, by
 
flies could have caused stains, containing blood of the victims, by
Line 229: Line 235:
 
teardrop-like stains was found to be highly suspicious for fly activity
 
teardrop-like stains was found to be highly suspicious for fly activity
 
(fig. 3 b).&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;<br>
 
(fig. 3 b).&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;<br>
<br>
+
 
 +
 
 
Additional tests under laboratory conditions on vertical paper surfaces
 
Additional tests under laboratory conditions on vertical paper surfaces
 
with adult Calliphora vicina Robineau-Desvoidy (Diptera: Calliphoridae)
 
with adult Calliphora vicina Robineau-Desvoidy (Diptera: Calliphoridae)
Line 235: Line 242:
 
and supplied with a reddish-brown food mixture, let to the following
 
and supplied with a reddish-brown food mixture, let to the following
 
results: <br>
 
results: <br>
<br>
+
 
 +
 
 
•&nbsp;&nbsp; &nbsp;After one day in a breedings cage, of 304 stains,
 
•&nbsp;&nbsp; &nbsp;After one day in a breedings cage, of 304 stains,
 
112 (36.8 %) had a round shape whereas 192 (63.2%) had a tear- or
 
112 (36.8 %) had a round shape whereas 192 (63.2%) had a tear- or
Line 247: Line 255:
 
left, 19.8% upwards right; 19.3% downwards left; 18.2% downwards right.
 
left, 19.8% upwards right; 19.3% downwards left; 18.2% downwards right.
 
&nbsp;<br>
 
&nbsp;<br>
 +
 
•&nbsp;&nbsp; &nbsp;The ratio Ltl/Lb was 1.5&nbsp; &plusmn; 1.6 (n =
 
•&nbsp;&nbsp; &nbsp;The ratio Ltl/Lb was 1.5&nbsp; &plusmn; 1.6 (n =
 
80) (i.e., tendency towards ratios &gt;1). <br>
 
80) (i.e., tendency towards ratios &gt;1). <br>
<br>
+
 
 +
 
 
However, single stains will not provide results that are statistically
 
However, single stains will not provide results that are statistically
 
sound. Although the ratio does not conclusively identify a stain as a
 
sound. Although the ratio does not conclusively identify a stain as a
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5.).<br>
 
5.).<br>
  
<br>
+
 
<b>3.5. Conclusion</b><br>
+
<font color=orange>3.5. Conclusion</font><br>
<br>
+
 
 
With information that stains appearing as human blood spatters were fly
 
With information that stains appearing as human blood spatters were fly
 
artifacts, coupled with other scene evidence, we felt confident that
 
artifacts, coupled with other scene evidence, we felt confident that
 
the possibility of an execution or revenge slaying could be put into
 
the possibility of an execution or revenge slaying could be put into
 
the mix of suspect behaviors at our crime scene.<br>
 
the mix of suspect behaviors at our crime scene.<br>
<br>
+
 
<b>4. Case II: Corpse of Lonely Woman</b><br>
+
 
<br>
+
<font color=orange>4. Case II: Corpse of Lonely Woman</font><br>
 +
 
 
In Summer 2001, a dead female person was found in her bedroom in an
 
In Summer 2001, a dead female person was found in her bedroom in an
 
urban appartment in Cologne, Germany. The body had entered dried-out
 
urban appartment in Cologne, Germany. The body had entered dried-out
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blow flies had been present, or if those dots had to be attributed to a
 
blow flies had been present, or if those dots had to be attributed to a
 
source to be investigated on. <br>
 
source to be investigated on. <br>
 +
  
 
The windows were closed before the police entered which explained the
 
The windows were closed before the police entered which explained the
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very clean and expensively furnished. The bathtub was half filled with
 
very clean and expensively furnished. The bathtub was half filled with
 
discolorated water that was most likely used to wash clothing. <br>
 
discolorated water that was most likely used to wash clothing. <br>
<br>
+
 
 +
 
 
Since the entrance door was regularly locked and no signs of a violent
 
Since the entrance door was regularly locked and no signs of a violent
 
fight were present, a reddish spatter field at a fan chain in the
 
fight were present, a reddish spatter field at a fan chain in the
Line 300: Line 313:
 
piece of paper. <br>
 
piece of paper. <br>
  
<br>
+
 
 
Because of the nature of the stains, they were neither taken into
 
Because of the nature of the stains, they were neither taken into
 
account for the further police investigation nor the reconstruction of
 
account for the further police investigation nor the reconstruction of
 
the events at the scene. The case was considered to be self neglect in
 
the events at the scene. The case was considered to be self neglect in
 
contrast to killing, or neglect by another person. <br>
 
contrast to killing, or neglect by another person. <br>
<br>
+
 
<b>5. Case III: Slaying of mother and child</b><br>
+
 
<br>
+
<font color=orange>5. Case III: Slaying of mother and child</font><br>
 +
 
 
On 30. January 2001, the dead bodies of a mother and her child were
 
On 30. January 2001, the dead bodies of a mother and her child were
 
found in the living room of their house on the border of the city of
 
found in the living room of their house on the border of the city of
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child that had been sleeping upstairs was alive and not hurt. Blood
 
child that had been sleeping upstairs was alive and not hurt. Blood
 
stain patterns were used to determine the course of events. <br>
 
stain patterns were used to determine the course of events. <br>
<br>
+
 
 +
 
 
The crime scene reconstruction based on blood spatter became important
 
The crime scene reconstruction based on blood spatter became important
 
to check the statements of an accused man who owned a knife that was
 
to check the statements of an accused man who owned a knife that was
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medico-legal considerations, it was thought that the velocity of the
 
medico-legal considerations, it was thought that the velocity of the
 
blood spatter might help to address theses questions. <br>
 
blood spatter might help to address theses questions. <br>
<br>
+
 
 +
 
 
Amongst numerous other reddish stains in the house (in this case, due
 
Amongst numerous other reddish stains in the house (in this case, due
 
to a local police procedure, all stains determined as originating from
 
to a local police procedure, all stains determined as originating from
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asked for by the police and later again requested by the judge during
 
asked for by the police and later again requested by the judge during
 
the trial.<br>
 
the trial.<br>
<br>
+
 
 +
 
 
The tiny, round stains on the lamp were distributed over the complete
 
The tiny, round stains on the lamp were distributed over the complete
 
surface (fig. 3). Genetic fingerprinting led to one conclusive DNA type
 
surface (fig. 3). Genetic fingerprinting led to one conclusive DNA type
Line 347: Line 364:
 
initial velocity but got slowed down due to the resistance of the air. <br>
 
initial velocity but got slowed down due to the resistance of the air. <br>
  
<br>
+
 
On the other hand, since a possible patterning as in fly artifacts
 
On the other hand, since a possible patterning as in fly artifacts
 
could could not be ruled out with certainty (fig. 3d), no absolute
 
could could not be ruled out with certainty (fig. 3d), no absolute
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fighting, inside of the room during the crime.<br>
 
fighting, inside of the room during the crime.<br>
  
<br>
+
 
<b>6. Practical hints</b><br>
+
<font color=orange>6. Practical hints</font><br>
<br>
+
 
 
From our case work experience and from our experiments, the following
 
From our case work experience and from our experiments, the following
 
suggestions and techniques are offered for use in differentiating
 
suggestions and techniques are offered for use in differentiating
 
between fly artifacts and human bloodstain patterns (fig. 4).<br>
 
between fly artifacts and human bloodstain patterns (fig. 4).<br>
<br>
+
 
 +
 
 
1. Document fly activity at a scene. Flies will be at a scene if access
 
1. Document fly activity at a scene. Flies will be at a scene if access
 
to the scene is available to them. They will stay at the scene as long
 
to the scene is available to them. They will stay at the scene as long
Line 375: Line 393:
 
Follow standard protocols of description of insects at crimes scenes
 
Follow standard protocols of description of insects at crimes scenes
 
[2,3,22] – where, when, how many?<br>
 
[2,3,22] – where, when, how many?<br>
<br>
+
 
 +
 
 
2.&nbsp;&nbsp; Document the range of stains. Fly activity will often
 
2.&nbsp;&nbsp; Document the range of stains. Fly activity will often
 
concentrate near light sources, on light colored walls, windows and
 
concentrate near light sources, on light colored walls, windows and
Line 381: Line 400:
 
Compare stains away from the body with stains near the body.<br>
 
Compare stains away from the body with stains near the body.<br>
  
<br>
+
 
 
3. Compare stains with known fly artifact patterns.<br>
 
3. Compare stains with known fly artifact patterns.<br>
<br>
+
 
 +
 
 
4. Identify suspected human bloodstain patterns that are of the "spot"
 
4. Identify suspected human bloodstain patterns that are of the "spot"
 
or "tear" drop pattern that offer a potential for use in reconstruction
 
or "tear" drop pattern that offer a potential for use in reconstruction
 
and eliminate the following:<br>
 
and eliminate the following:<br>
<br>
+
 
 +
 
 
a. Stains that have a tail/body (Ltl/Lb) ratio greater than one,<br>
 
a. Stains that have a tail/body (Ltl/Lb) ratio greater than one,<br>
 +
 
b. Stains with a tadpole/sperm type structure, <br>
 
b. Stains with a tadpole/sperm type structure, <br>
c. Stains with a sperm cell type structure that do not end in a small
+
 
dot, <br>
+
c. Stains with a sperm cell type structure that do not end in a small dot,<br>
 +
 
 
d. Any stains without a distinguishable tail and body, <br>
 
d. Any stains without a distinguishable tail and body, <br>
 +
 
e. Any stains with a wavy and irregular linear structure, <br>
 
e. Any stains with a wavy and irregular linear structure, <br>
  
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Cast off human blood will produce stains, within a group, that
 
Cast off human blood will produce stains, within a group, that
 
indicates a common general convergence point.<br>
 
indicates a common general convergence point.<br>
<br>
+
 
 +
 
 
5.&nbsp; Note the absence of known human bloodstain pattern
 
5.&nbsp; Note the absence of known human bloodstain pattern
 
characteristics. The absence of misting around a concentrated mass
 
characteristics. The absence of misting around a concentrated mass
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Within a group, human cast off patterns often leave secondary wave cast
 
Within a group, human cast off patterns often leave secondary wave cast
 
off patterns and run off patterns.<br>
 
off patterns and run off patterns.<br>
<br>
+
 
 +
 
 
6. Cover blood stains, especially on the floor, with paper sheets to
 
6. Cover blood stains, especially on the floor, with paper sheets to
 
prevent them being destroyed by investigators walking on the stains. <br>
 
prevent them being destroyed by investigators walking on the stains. <br>
<br>
+
 
 +
 
 
7. One or two stains do not make a case. Stains that could be fly
 
7. One or two stains do not make a case. Stains that could be fly
 
artifacts should be eliminated and an evaluation based upon stains that
 
artifacts should be eliminated and an evaluation based upon stains that
 
can be explained in terms of origin and relevance to the
 
can be explained in terms of origin and relevance to the
 
reconstruction. <br>
 
reconstruction. <br>
<br>
+
 
 +
 
 
8. Use a high resolution camera with a macro lens and include a scale
 
8. Use a high resolution camera with a macro lens and include a scale
 
in every single picture.<br>
 
in every single picture.<br>
<br>
+
 
  
 
Forensic scientists, crime scene technicians and investigators may
 
Forensic scientists, crime scene technicians and investigators may
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an informed identification, or at least advanced documentation of such
 
an informed identification, or at least advanced documentation of such
 
stains. <br>
 
stains. <br>
<br>
+
 
<b>Acknowledgements</b><br>
+
 
<br>
+
<font color=orange>Acknowledgements</font><br>
 +
 
 
Dr. Brett Ratcliffe, University of Nebraska (Lincoln), performed the
 
Dr. Brett Ratcliffe, University of Nebraska (Lincoln), performed the
 
species determination of the flies and kindly agreed that his findings
 
species determination of the flies and kindly agreed that his findings
Line 439: Line 468:
 
crimes scenes for case work as well as research purposes. The reviewers
 
crimes scenes for case work as well as research purposes. The reviewers
 
provided us with excellent comments.<br>
 
provided us with excellent comments.<br>
&nbsp;<br>
+
 
<b>References</b><br>
+
 
<br>
+
<font color=orange>References</font><br>
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Revision as of 20:21, 20 September 2016

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Source: Forensic Science International 137 (2003) 152-159

Distinction of bloodstain patterns from fly artifacts

[More articles from MB] [Articles about MB]

BY MARK BENECKE 1* and LARRY BARKSDALE 2

1 International Forensic Research & Consulting, Postfach 250411, 50520 Cologne, Germany, E-mail forensic@benecke.com
2 Lincoln Police Department, 575 South 10th Street, Lincoln, Nebraska 68502, USA; lpd211@cjis.ci.lincoln.ne.us

  • corresponding author


Abstract/Summary

Forensic scientists may encounter blood spatter at a scene which may be pure or a mixture of fly artifacts and human bloodstains. It is important to be able to make an informed identification, or at least advanced documentation of such stains since the mechanics of production of fly artifacts are not determinable to the crime scene reconstructionist from regular police forces.


We describe three cases in which experiments and crime scene reconstruction led to additional information. Case 1: Above the position of a victim, numerous blood stains of the low-high velocity type were found. Exclusion of these stains being caused by force (but instead caused by the activity of adult blow flies) by use of the following observations that were confirmed in experiments: a) Sperm-/tadpole-like structure with length > width, b) random directionality c) mixture of round symmetrical and teardrop shaped stains. Case 2: A reddish spatter field was found on a fan chain two rooms away from the place where a dead woman was found. Localization of the spatter on the bottom end of the surface hinted strongly towards fly activity. Case 3: Double homicide; submillimeter stains were found on a lamp between the two corpses. Activity of flies was less likely compared to alternative scenario of moving lampshade and violent stabbing.


Key Words

Blow Flies, Forensic Entomology, Blood Stain Pattern Interpretation, Blood Spatter Artifacts


1. Introduction

In the last years, forensic entomology [1-7] and blood stain pattern analysis [8-19] became more and more part of forensic investigations and trials [14] outside of the United States.  


In this context, crime scene experts often note that flies might leave information that could produce confusion within the scene. The mechanics of production of fly artifacts are not determinable to the crime scene reconstructionist from regular police forces, since regurgitation and defecation from a fly are frequently not taken into account.


Only old German texts [8] and modern text books from the United States mention artifacts produced by flies [16-19], e.g.:


"The activity of flies at the scene where blood has been shed is another possible source of small stains of blood that may be confused with medium- to high-velocity impact spatter... An understanding of the mechanics of flies feeding on blood an decomposing bodies is essential for proper interpretation of these bloodstains. The horse fly is characterized as a biter, while the common house fly is specialized as a lapper and sucker. Flies ingest blood and regurgitate it onto a surface to allow enzymes to break down the blood. At a later time, the flies return to the areas of regurgitated blood and consume a portion of the blood.


The surfaces upon which these activities have taken place will contain small spots of blood material which are often a millimeter or less in diameter with no definite point of convergence or origin. Some of the stains will exhibit dome shaped craters due to the sucking process and others may show swiping due to defecation. These stains may be observed on many surfaces at the scene expecially lamp shades, blinds and ceilings as well as on the victim and clothing. Their locations may be inconsistent with blood spatter associated with injuries sustained by the victim." [19]


Although not true spatter, another pattern often confused with spatter is the "fly speck" or "fly spot" pattern. Flies present within the scene will feed on blood found there. This blood is both tracked about and regurgitated by the flies. In the instance of the tracking pattern, the marks are extremely small but a pattern may be evident on close examination.


In the case of regurgitation, the specks are remarkably symmetrical....Most often, the analyst finds these patterns in warm areas where the flies rest, such as high in window corners or along walls where the sun strikes. Such stains will usually test positive for blood with a presumptive test. Obviously, care should be exercised in evaluating any abnormal patterns which meet these criteria." [10]


However, no integrated approach by natural sciences and criminalists had been used until actual case work (see cases below) and presentation in courts, made it necessary to develop a method to safely distinguish between blood spatter caused by force and blood spatter-like patterns produced by flies.


This is expecially important since even artifacts caused by flies may very well include the vicitim´s blood. Neither presumptive blood tests like Hemastix (2190)/Heglostix (Bayer 028165A; hemoglobin catalyzes oxidation of 3,3´, 5,5´tetramethylbenzidine (color reagent) by diisopropylbenzole dihydroperoxide from green to blue), Sangur (Merck), or Luminol, nor DNA typing will differentiate between the two types of stains. This leaves recognition of stain patterns and other physical information as the relevant criteria. The following text illustrates stains produced by the activity of flies and suggests methodology for evaluating stains in a decomposed body scene.


Furthermore, from the above quotes it appears that some documentation of the crate was possible. In many countries, it is however unlikely that a blood stain pattern expert will enter he actual scene and therefore, documentation of crates has, to our knowledge and does usually never take place.


2. Blood Spatter Types

Blood that is subjected to a low velocity impact (less than 1.5 m x s-1); resulting blood spots often around 4-8 mm in diameter) is called low velocity blood spatter. It is caused by free-falling blood under the influence of gravity, including blood cast off from fist shoe, or weapon.


Blood spatter as reported in the following three cases was usually thought to be caused be either high velocity impact, or by a mixture of medium to high velocity impact. Those types of spatter are defined as blood subjected to a medium velocity impact (about 7.5-30 m x s-1), e.g. blows with a hammer, or axe (medium velocity; spots typically measuring about 4 mm in diameter), or blood sources that are subjected to a high velocity impact (>7.5 m x s-1), e.g. a gunshot (blood spots typically < 1 mm in diameter) [9].


3. Case I: Double homicide in Nebraska

3.1. General Scenario

The remains of two men were discovered at 14:25 hrs on 14. June 1997 in in a third level apartment in a five-plex apartment building in urban Lincoln, Nebraska, USA [23].


Both victims were fully clothed; both had a gunshot wound to the head and gunshot wounds to the torso. One victim was found face down in the kitchen area and the other victim was prone on the living room floor on carpeting. Pools of a reddish substance were observed around the bodies of the victims.


The bodies were in the active decay stage with black putrefaction only just beginning; the skin was intact everywhere except where there were gunshot wounds. At the wound sites, there was dried blood and body fluids and in the areas around the bodies, flies, maggots and pupae as well as some adult flies were present. The temperature registered 30 °C on the wall thermostat.


3.2. Forensic Entomology

On 15. June 1997, at 06:45 hrs, the police collected six adult flies, three third instar fly larvae and several hundred first instar fly larvae in ethanol from the scene. Adult flies had probably gained access to the apartment by an open space beneath the front door. Both adults and larvae were identified as Phormia regina (MEIGEN) (Diptera:Calliphoridae) [20], the black blowfly and concluded from the presence of small, first instar larvae and large, third instar larvae that two distinctly separate periods of egg-laying by adult flies had taken place.


3.3. Blood Stains

Initial observation of the scene gave the appearance of extensive low, medium and high velocity blood spatters. Above the position of one of the victims numerous stains of the low-high velocity type were found (fig. 1). Similar areas were found on a kitchen hanging lamp, the interior and exterior of the entry door, the bathroom, the two bedrooms and the walls around the victims. The stains were tested positive for blood with a quick test for hemoglobin (Hemastix/Heglostix)


The first assumption to be made was that there had been slinging of a lot of blood around the kitchen and living room. This would suggest not only gunshot wounds, but considerable movement of the victim and suspect(s). It could suggest a motive of robbery, burglary, assault, or a surprise attack. Examination of the kitchen and living room did neither indicate struggling or fighting to any great amount. In the bedrooms and bathroom there were flies, but no signs of bloodstain patterns. There were no maggots in these rooms. The conclusion we made was that not much activity had taken place in the bedrooms or the bathroom of an assaultive nature and the bloodshed had taken place in the kitchen and living room.


Recostructing the angle of impact of many of those stains, however, led nowhere. There was no indication that the bodies had been moved and there were no signs of a struggle in the bedrooms, or bathroom. Smaller, round type spatters were mostly < 3 mm in length and > 1  mm in diameter. Furthermore, stains of a sperm-like shape (irregular, uneven form with tail much longer than the body) as well as a missing systematic directionality were observed. Since all stains were composed of blood, how did they (a) get into all of the rooms and (b) transferred to the walls?


3.4. Experiments and Measurements at the Scene of Crime

It is known that after feeding, flies regurgitate and defecate. Hence, flies could have caused stains, containing blood of the victims, by regurgitation, defecation and transference. In such cases, it is expected that presumptive blood tests would indicate the presence of blood. To prove that the unusual bloodstain patterns originated from the body of the victims, whereas the mechanism of transfer was provided by adult flies, the ratio Ltl/Lb (lenth of tail/length of body) was calculted as 3,3 ± 2,4 [table 1]. Such a high value will not be reached unter most case conditions, especially since not only the calculated angles of impact but also the directionality of the stains never point into one direction as would be expected from a violent impact on a source of blood. Also, a mixture of round, symmetrical and teardrop-like stains was found to be highly suspicious for fly activity (fig. 3 b).      


Additional tests under laboratory conditions on vertical paper surfaces with adult Calliphora vicina Robineau-Desvoidy (Diptera: Calliphoridae) blow flies matured and maintained at room temperature (20 -- 25°C) and supplied with a reddish-brown food mixture, let to the following results:


•    After one day in a breedings cage, of 304 stains, 112 (36.8 %) had a round shape whereas 192 (63.2%) had a tear- or sperm-like shape.

•    The directionality measured along the longer axis of the tear- and sperm-like stains did show a random distribution of stain orientations with an artificial  preference for the top left where a window (light source) was situated. In this experiment, orientation was directed into the following directions: 42.8% upwards left, 19.8% upwards right; 19.3% downwards left; 18.2% downwards right.  

•    The ratio Ltl/Lb was 1.5  ± 1.6 (n = 80) (i.e., tendency towards ratios >1).


However, single stains will not provide results that are statistically sound. Although the ratio does not conclusively identify a stain as a fly artifact, it provides a tool to eliminate suspect stains (see also 5.).


3.5. Conclusion

With information that stains appearing as human blood spatters were fly artifacts, coupled with other scene evidence, we felt confident that the possibility of an execution or revenge slaying could be put into the mix of suspect behaviors at our crime scene.


4. Case II: Corpse of Lonely Woman

In Summer 2001, a dead female person was found in her bedroom in an urban appartment in Cologne, Germany. The body had entered dried-out state of decay with severe undernourishment during lifetime and an underlying minimal greenish discoloration of the face and the abdominal area after death. In the anal region of the corpse, few blow fly maggots (oldest larval stage L3) were found. As soon as the windows were opened, adult Lucilia sp. entered the room. Therefore and because of numerous dots in the face of the dead person, the police asked if blow flies had been present, or if those dots had to be attributed to a source to be investigated on.


The windows were closed before the police entered which explained the presence of only few flies, mostly pupae of phorids (Diptera: Phoridae), was in accordance with the reconstruction of events. Apart from piles of empty pizza delivery cardboard boxes and cigarette butts, which did not provide food sources for blow flies, the appartment was very clean and expensively furnished. The bathtub was half filled with discolorated water that was most likely used to wash clothing.


Since the entrance door was regularly locked and no signs of a violent fight were present, a reddish spatter field at a fan chain in the kitchen became of interest (fig 3 c,d). The kitchen was located two rooms away from the sleeping room and there was no visible evidence that linked the kitchen to any violent event. Closer examination led to the conclusion that the stains were fly artifacts. Since the eyes of the corpse were still intacts and not used as a food resource by maggots, it was concluded that only very few adult individuals of a smaller fly species had been living in the appartment at some point before, or at the time of death. Those few individuals used the fan chain as a resting place and deposited reddish material with a typical preference fort he lower border of the surface. The same effect is present in fig. 3a under laboratory conditions, yet in a much larger scale, where the flies also preferred the bottom border of the hanging piece of paper.


Because of the nature of the stains, they were neither taken into account for the further police investigation nor the reconstruction of the events at the scene. The case was considered to be self neglect in contrast to killing, or neglect by another person.


5. Case III: Slaying of mother and child

On 30. January 2001, the dead bodies of a mother and her child were found in the living room of their house on the border of the city of Cologne, Germany. They had been dead for around six hours. Another child that had been sleeping upstairs was alive and not hurt. Blood stain patterns were used to determine the course of events.


The crime scene reconstruction based on blood spatter became important to check the statements of an accused man who owned a knife that was used for the stabbing. For legal technicalities (rights of inheritance) it also became important if the woman, or her child had been killed first. Thridly, the defense lawyer wanted to proof that his client had stabbed the child with brutal force to make clear that his client had no mental control in the moment he performed the stabbing. Apart from medico-legal considerations, it was thought that the velocity of the blood spatter might help to address theses questions.


Amongst numerous other reddish stains in the house (in this case, due to a local police procedure, all stains determined as originating from the victims by DNA typing), few very small stains on a lamp were observed. This lamp was located only ca. 1,80 m over ground and had been hanging directly between the locations where the two bodies were found. The police asked if these stains were caused by the impact of violence, or by flies. As in most cases, the presence of flies was not looked at by the first team which entered the house through a window. After that, all flies may have flown out of the window. Therefore, a combined blood spatter and forensic entomology expert statement was asked for by the police and later again requested by the judge during the trial.


The tiny, round stains on the lamp were distributed over the complete surface (fig. 3). Genetic fingerprinting led to one conclusive DNA type out of six stains (DNA of the child was found in one stain, no result in the other stains). It was discussed that the stains might have originated from the offender´s knife that got stuck in the vertebra of the child (as documented by the forensic pathologist). When the offender took the knife out of the bone with a jerk, few tiny droplets of blood may have been distributed with a relatively high initial velocity but got slowed down due to the resistance of the air.


On the other hand, since a possible patterning as in fly artifacts could could not be ruled out with certainty (fig. 3d), no absolute statement could be made about the nature of these stains. In the court, we reported that because of the season of the year (winter) and the state of the house (no rotting organic material present), it was less likely that flies had produced the stains but that it was more likely that the blood actually shed off the knife during the stabbing. Droplets then reached the lamp at least at two seperate events whilste the lamp was rotating around ist axis. Since the lamp was located ca. in the height of an adult central European person´s head, rotation was most likely induced by the people moving and maybe fighting, inside of the room during the crime.


6. Practical hints

From our case work experience and from our experiments, the following suggestions and techniques are offered for use in differentiating between fly artifacts and human bloodstain patterns (fig. 4).


1. Document fly activity at a scene. Flies will be at a scene if access to the scene is available to them. They will stay at the scene as long as a food source is available to them and/or as long as they are trapped. Therefore, check for dead flies, too. If evidence of flies is present at the scene, assume that fly artifacts will be at the scene. Follow standard protocols of description of insects at crimes scenes [2,3,22] – where, when, how many?


2.   Document the range of stains. Fly activity will often concentrate near light sources, on light colored walls, windows and mirrors. They will often be present in rooms away from the body. Compare stains away from the body with stains near the body.


3. Compare stains with known fly artifact patterns.


4. Identify suspected human bloodstain patterns that are of the "spot" or "tear" drop pattern that offer a potential for use in reconstruction and eliminate the following:


a. Stains that have a tail/body (Ltl/Lb) ratio greater than one,

b. Stains with a tadpole/sperm type structure,

c. Stains with a sperm cell type structure that do not end in a small dot,

d. Any stains without a distinguishable tail and body,

e. Any stains with a wavy and irregular linear structure,

f. Any stains that do not participate in directionality consistent with other stains that suggest a point of convergence at a point of origin. Larger fly artifacts, within a group, will point in all directions. Cast off human blood will produce stains, within a group, that indicates a common general convergence point.


5.  Note the absence of known human bloodstain pattern characteristics. The absence of misting around a concentrated mass would suggest the stains might not be from human cast off blood origin. Within a group, human cast off patterns often leave secondary wave cast off patterns and run off patterns.


6. Cover blood stains, especially on the floor, with paper sheets to prevent them being destroyed by investigators walking on the stains.


7. One or two stains do not make a case. Stains that could be fly artifacts should be eliminated and an evaluation based upon stains that can be explained in terms of origin and relevance to the reconstruction.


8. Use a high resolution camera with a macro lens and include a scale in every single picture.


Forensic scientists, crime scene technicians and investigators may encounter blood spatter at a scene which may be pure or a mixture of fly artifacts and human bloodstains. It is important to be able to make an informed identification, or at least advanced documentation of such stains.


Acknowledgements

Dr. Brett Ratcliffe, University of Nebraska (Lincoln), performed the species determination of the flies and kindly agreed that his findings were used in this article (Case 1). Saskia Reibe, University of Cologne, performed many of the measurements in laboratory conditions (Case 1). Prof. Klaus Hausen and Mucki Döring, Universiy of Cologne, kindly allowed us to us to use his flies and fly stables from his neurophysiological laboratory for experimentation. The Cologne Homicide Detective´s Bureau (KK 11; Cases 2 and 3: Detectives Frank Kolvitz and Rolf Wingert) and the Cologne KK 53 (Crime Scene Unit, head: Achim Wolff) were and are most helful in inviting me to crimes scenes for case work as well as research purposes. The reviewers provided us with excellent comments.


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