Amy Degaro: Forensic Entomology

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http://www.benecke.com/ proudly presents:

Amy Degaro: Forensic Entomology & Interview with Mark Benecke

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By Amy Degaro, Northern Kentucky University, Criminology Class 2003

Includes in Interview with Mark Benecke

Introduction and History:

Forensic Entomology is the use of insects and other arthropods that inhabit decomposing remains to aid legal investigations. It can be broken down into three types of areas: medicolegal, urban, and stored product pests. Medicolegal is the criminal component of the legal system, which deals with the feeding insects that have infested human remains. A second area called urban deals with the insects that affect humans and their environment. The urban area has both criminal and civil components, because the insects will feed off the living and the dead. The last are deals with stored product insects and these are found in foods. The entomologist can check the bugs for any type of food contamination that may have occurred.

Forensic entomology’s history first came about in 1235 A.D. by a Chinese “death investigator” named Sung Tz’u. He wrote a book entitled The Washing Away of Wrongs that talked about forensic science. The first actual medicocriminal entomology case was talked about in his book. Sung talked about how a murder happened in a Chinese village and how the local death investigator solved the crime. The investigator questioned all the villagers and then had them bring their sickles (since the murder was a slashing) to a spot to have flies tell which sickle was used. The flies were attracted to a particular sickle probably because of invisible remnants of human tissue. The owner of the sickle confessed to the crime.

In later years and more technical advances Francesco L. Redi (1668) studied rotting meat that was exposed to or protected from flies. From this he disclaimed spontaneous generation, because until then it was thought that maggots could just come from rotten meat. In 1885 Bergeret became the first westerner to use insects as forensic indicators. There was a case that included babies’ remains to discover this. A baby’s body was found behind some plaster mantle in a house so an investigation was conducted. On the body was an assemblage of insects that Bergeret determined as having been there for several years.

In past years research has been done on the bugs themselves. First of all the insects need to be classified as to what they are, they need to be described and their evolutionary relations of the various forms of life. This is also known as taxonomy and systematic classification, which is very important to the entomologist so they can look at the birth to adulthood and types of things the insects eat. A concept called “lock and key” can isolate the reproduction organs of the insects that enables them to tell if insect is male or female.

Two common insects used are Blowflies and Beetles. These insects undergo a complete development where there is an egg stage, and then the egg hatches into a larval form and undergoes incremental growth. This growth pattern is caused by the shedding of the outer skin that the larvae must go through before it enters that inactive pupal stage. This pupa is the hardened outer skin of the last larval stage that protects it so it can then become the adult. Not all insects go through complete growth such as cockroaches. What happens with then is the egg hatches into an immature, which resembles the adult form, but it is smaller and does not contain wings. These developments are important to the forensic entomologists so they can tell how long a body has been dead.

In the Blowflies the females will lay their eggs in places such as nose, eyes, ears, anus, penis or vagina and any wounds on the body. The insects age will help lead to the time of death of the deceased. In order to get the insect’s age many studies have been conducted to watch the growth. With Blowflies the eggs are laid and are about two millimeters in length. In the first eight hours there is little or no signs of development. Usually the egg stage will last about one day then turns into larvae. There are three instars or stages of the larvae. In the first it is usually about five millimeters in length after 1.8 days, the second is about ten millimeters long after 2.5 days and in the third stage it is about 17 millimeters long after four to five days. Temperature, climate, humidity and dependence of insect will have an effect on the growth. The third stage also known as Prepupae is when the larvae start to move around and moves away from the body. This stage is seen within eight to twelve days after egg has been laid. In the Pupa stage the skin becomes darker and are seen within 18-24 days. If no pupae are on the body then it is safe to say that the body has been there at least 20 days or more. There are other insects that arrive within certain days, but flies are most important, because their life cycle can be determined.

Stages of Decomposition With Bug Determination:

Ants and wasps also come within the first day or two. The ants feed on the fly larvae and the wasps feed on adult flies and also the body’s remains. This is known as the first or fresh stage of decomposition. The second stage or Bloated stage involves houseflies, which come to site within two to six days. The houseflies may lay eggs that will hatch in five days. The ants and maggots are still busy in this second stage. The third or decayed stage involves day’s seven to eleven. In this stage the third larvae stage are present. Then beetles arrive to feed on dry skin and cartilage. The beetles’ larvae are usually present on the 11th day. Ants’ activities during this stage begin to slow, because there are less and less larvae. The fourth stage can also be called Mummified stage and these are days 12-25. Beetles have an increase in their numbers. Post Decay (fifth) stage is from days 10-23 and other animals or insects is eating mostly maggots. The last stage is the Remains stage and this is from day 26 on. Beetles will be present up to 50 days. This information about the stages of death and what insects are there is important to a forensic entomologist, because from the species succession, larval weight and larval length they can tell how long a body has been dead. It is necessary to know when the person died so investigators can have a starting point in the case. Also the forensic entomologist can make inferences about if the body was moved after death. They can tell this by the location and what insects are on the body. An example of this would be Fly A prefers being indoors, whereas Fly B prefers being outdoors. A body is found with Fly A and it’s eggs outside so it can be inferred that the person must have been killed inside and then later taken outdoors. Another inference about the environment in which the person was kept in is if no insects are about then the body could have been kept in frozen or wrapped up.

Abuse and rape can be determined by entomologistical evidence. Victims that are bound, drugged, or in some other way helpless will have fecal or urine soaked clothes. Fecal and urine attract certain types of flies making it possible for forensic entomologist to come out with those types of stains. Other evidence such as DNA of human blood can be recovered from the insect’s digestive tract. From the DNA found it is possible to come up with a suspect, because either the suspect’s DNA was found or found out who victim was and from thee could make inferences about who killed person. Since insects eat away at the corpses evidence can be lost, but with the help of this DNA and toxicological analysis on the insects themselves, it is possible to get any drugs or toxins in the human tissue prior to death.

Collecting Evidence:

Collecting the evidence is a slow and careful process. The forensic entomologist needs to ever so careful when collecting the evidence, because if not he/she could ruin other evidence observations of the area surrounding the body should be noted. Entomological Investigation of the Death Scene in Entomology and Death: A Procedural Guide by E.P. Catts and W.H. Haskell are as follows: 1) observations of the scene should talk about the general habitat and location of the body in reference to vegetation, sun/shade conditions and it’s proximity to any open doors or windows if possible. The locations of the insects and what stage they are in should be noted. 2) Collection of climatologically data at the scene. Data should include: a) ambient air temperature at the scene taken about at chest height with thermometer in shade. b) Maggot mass temperature (place thermometer into larvae mass center). c) Ground surface temperature. d) Temperature at the interface of the body and ground. e) Temperature of soil under the body. f) Weather data that includes minimum and maximum daily temperature and rainfall from a period of one to two weeks before victim’s disappearance to three to five days after body was found. 3) Collections of insects from the body at the scene. Insects such as adult flies and beetles should be collected first, because they will leave crime scene fast once it has been disturbed. A net can be used to catch them and once caught they are to be put into a glass container that contains cotton balls soaked in ethyl acetate. This will immobilize the insects and when this occurs they may be placed in a tube that consists of 75% ethyl alcohol. A collection label should be made up that consists of: geographical location, date and hour of collection, case number, location on the body where removed, and name of collector. Once the adults have been collected then the larval collection may be begin. The investigator must look for any presence of eggs the larvae should be apparent. A sample of 50-60 larvae should be collected and put into ethyl alcohol. Another way to preserve the maggots are to place them in boiling water for about 20 seconds, but either way must be noted. A duplicate sample should be made for live insects and these can be placed in a container with moist toweling and tiny air holes. Soil samples should be taken underneath body and around body if outdoors. All samples must be labeled properly.

Case Studies:

Below are a couple cases that have been processed by forensic entomologist and how effective insects can be in determing time of death, movement of body, and any post/antimortem wounds.

This first case was documented by Wayne D. Lord, Federal Bureau of Investigation, Washington D.C. The remains of a murder victim were reportedly thrown down an open well on a small farm in a rural are in south-central Indiana. Then the well was completely filled with junk, tires, and rocks. The exact location of the well where the remains were deposited was unknown, but as the investigators drove into one of several wooded farmyard sites being investigated, it was obvious they had found the right location. Several thousand flies were hovering over a pile of old tires. The remains were found at the bottom of the well under the debris. Decomposition was advancing in the body, but there were no insects found on it. Access to the body by blowflies was prevented by the intervening material, but odors were still capable of attracting multitudes of insects. (Lord, 2002)

Another case found by Mark Benecke goes like this: the corpse of a 66 year old man (back-calculated alcohol level at time of death: 1.07 parts per thousand) was
found dead on the balcony of his flat on the eighth floor of a urban building in Cologne. The corpse was thought to have been there for 25 days, from 31. August 1996 to 25. September 1996. The soft tissue of the face, neck and right ear was destroyed by maggots; the skin was greasy and colored greenish-brown, the abdomen was bloated. Masses of maggots were found on the corpse.

A single fly, which was reared, to adult was identified as Parasarcophaga argyrostmoa. In Cologne, P. argyrostmoa is only found near muck heaps, on food containers in Zoological Garden. Until now, in Cologne it has never been seen on corpse inside flats. Until now no information on the indepence of the height of a flat and colonization of corpses was determined systematically. For that reason, P. argyrostma seems to be a highly indicative species, which tells if a corpse, which was found in, a more or less closed environment was lying outside on the balcony for some time. P argyrostma might therefore turn out to be of special help in forensic investigations in urban surroundings like the city of Cologne which suffer from a fauna with a clearly restricted number of species to check whether a corpse was lying outside flat-even on a balcony-or not. (Benecke, 1998:43).

Interview:

I wrote to three different people and all responded but I chose Mark Benecke, because he gave me the most information and was more interesting.

In the interview I emailed him a list of questions and he gave his replies.

Amy: What is your full title?

Mark: My title is Dr. Mark Benecke. I have a Ph. D. and I am a certified Forensic Biologist.

Amy: How did you get into this field?

Mark: During my studies of biology at the University of Cologne in Germany, I realized that humans are less than unimportant life-forms on Earth and that insects rule in each and every sense of the meaning. It was there as a university student that I first became interested in invertebrates, animals without a spine. I spent my nights searching for tropical snails and roaches in our Zoological Garden’s terrarium building and my days performing genetic fingerprints of microscopic roundworms and rotifers, as well as training the eight armed octopus to unscrew a glass filled with its favorite food. My professional ties to the DNA typing lab at our local University Institute for Forensic Medicine, as well as any strong desire to work in a multidisciplinary field, is ultimately what brought me into forensic DNA work.

Amy: How valid do you think the findings are? On a scale from 1-10 how many times would you say the findings are correct?

Mark: We report probabilities, not true or false answers.

Amy: Do you think that the bugs are used more in guilt or innocence?

Mark: I do not know, because I am not interested in guilt, I only work with biological stains to find the truth. Truth is not necessarily related to guilty or not.

Amy: Do you think that forensic entomology has helped to prove more cases than without it at all?

Mark: F.E. is just one more method—the more methods you got in your toolbox the better.

Amy: Are bugs admissible in courts as evidence?

Mark: F.E. can easily be used in courts when the expert is an expert.

Amy: How many yeas of schooling and types of schooling?

Mark: Depends on the country (i.e. legal system) you work in.

Amy: What is your greatest reward in regard to what you do with this subject?

Mark: Truth. Variety of cases.

Amy: With the public’s knowledge about this subject would it be possible for someone to plant evidence to throw off an investigator?

Mark: It is too difficult. But even if I committed a crime and tried to change the entomological evidence that would not mean that the police would be misled. An investigation is an intelligent process that should be resistant against getting misled by one single stain.
This interview was very interesting, because this guy is one smart cookie. Mark is from Germany and his main areas of professional interest lie in DNA typing, forensic entomology, criminalistics, and invertebrate zoology. Mark has worked just about anywhere you can imagine in Biology and Legal issues. Attached is a page showing what all he has done. This is a very interesting man and I think it is so neat that he is from Germany and could give me some of his perspectives. Attached is a website that he referred me to in the interview about himself. I thought you might like to look at it. It is a bibliography about him.



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