Forensic entomologist

Forensic entomologists are those involved in the branch of entomology that involves insects and violent crime or the law, known as forensic entomology. This includes three main branches: medicocriminal entomology, urban entomology, and stored product entomology. It takes discipline and accomplishment to perform the tasks of all the diverse jobs forensic entomologists perform such as: crime scene investigation, research, and teaching at universities. The education required to become a forensic entomologist is extensive and falls into two major categories: undergraduate and graduate level study. Forensic entomologists today are performing new research to broaden our knowledge of insects and how they can be beneficial to the population. Many network with each other by forming groups such as the American Board of Forensic Entomology(ABFE), the North American Forensic Entomology Association (NAFEA) and the European Association of Forensic Entomology. Often their expertise can then be used in the court system to solve various cases. Forensic entomologists work has played a major role in some famous cases as well as daily life.

Forensic Entomologist

Data Collection

Forensic entomologists are required to take copious amounts of data at the scene. An intense amount of time and energy go into to data collection because everything they collect and observe must hold up in the court of law. The first portions of information gathered include the climate of the area, both during the time of initial contact to within three to five days afterward. One to two weeks afterward may be required to estimate a rough post mortem interval. Climate approximation is imperative for determining the specific life cycle of insects found at the scene. Good or harsh conditions will either speed up or slow down insect development which gives important information regarding how long the victim may have been decaying.^[1] In addition to climate, ambient air, soil (around and below the body), and maggot mass, temperatures are needed since they are essential to determining the speed of growth of the insects collected during the investigation. All documentation must be concise to avoid confusion. A death scene form is one of the most important tools a forensic entomologist has. He or she can make note of many key observations quickly such as placement of the maggot mass on the body, temperatures, and stage of decay.^[2] The evidence must be able to pass through the “chain of evidence” (the process of using evidence legally in the judicial system) without fear of contamination, tampering, or any other outside variable that could affect its legitimacy during trial in a court of law.

Ten Basic Rules for Collection

Conditions vary when it comes to arthropod collection and sometimes local procedural regulations apply. However, Mark Benecke developed the following basic guidelines which are used by federal agents of the F.B.I., the Bundeskriminalamt in Germany, and rookie forensic entomologists:

1. Take good close-up photos of all locations from which arthropods are collected. The state of decomposition can change greatly within hours due to insect activity and weather conditions. Also mite bites should be noted.

2. Since maggots tend to become invisible and “flash out” when photographed, do not use flash photography, especially on digital photos.

3. Always use a metric and an inch scale on every picture taken to determine the length of the larvae. The use of international scales is important due to different units of measurement in different countries.

4. Gather one spoon full of insects from at least 3 different areas of the crime scene and the body and place into 3 clearly labeled jars.

5. Do not put insects in isopropyl or formalin. Instead use 98% ethanol for half of the insects collected.

6. Kill the insects with hot water before placing in ethanol.

7. Place half of the specimens in a cool, refrigerated place if available.

8. Label everything excessively with dates, initials, exact times, and locations.

9. Ask an experienced forensic entomologist any questions that arise.

10. Identification must be performed by an experienced entomologist. Keys that are applicable to the local fauna may be used.^[3]

Tools

Forensic entomologists use a variety of tools to determine post-mortem interval:

• Net
• Sticky Traps
• Vials/Kill Jars
• Preservation Chemicals: Ethyl Alcohol and Acetone
• Latex Gloves
• Forceps
• Live Specimen Containers
• Shovel
• Thermometers
• Labels (both adhesive and non-adhesive)
• Small Paint Brushes
• Foil
• Vermiculite and Food
• Graphite Pencil
• Hand Towel
• Camera
• Ruler
• Paper Towels
• Sifting Screens
• Death Scene Form

Insect Collection

Collection of adult insects in the area, including flies and beetles, follows as they may become disturbed enough to leave due to the high amount of law enforcement personnel in the vicinity. The most common method is sweep netting, although sticky traps placed near the corpse are utilized as well. Collection of insect adults provides a basis as to what species may be on the corpse in larval form. Collection of larvae is the next step as it is the main route of PMI determinance. Flies prefer to deposit their eggs in any available orifice on the body such as the eyes, ears, nose, anus and mouth. They will also utilize any open wounds to give the developing offspring easier access to necrotized(dead) flesh to feed upon. Different species of larvae have different migration patterns. This refers to the stage of life where they are preparing to pupate, so they migrate away from their original food source to a safer region less vulnerable to prey. It is up to the forensic entomologist on scene to not only collect from around the body itself, but also directly under it. Some larvae burrow up to 3 feet (0.91 m) in the ground as well so some digging is required. If the corpse is in an advanced state of decomposition, samples of the morgue chamber climate and insects present from the body bag and during autopsy must be taken as well. Overall, two types of collections are taken: one for immediate observation (preserved using boiling water and “kill jars” or ethyl acetate) and one for insect rearing for larval or pupal identification. Both methods help provide a positive identification for the insect genus and species. One of the most important facets of the forensic entomologist's job is documentation.

Collection During an Autopsy

It is essential that an experienced and knowledgeable forensic entomologist is present at the crime scene to ensure thorough use of entomological evidence. Sometimes, if an investigation is not carried out to its full potential, the entomologist will attend the autopsy and work alongside a forensic pathologist (98).

The corpse will most likely arrive at the morgue in a “body bag”, especially if the corpse is in an advanced state of decay. Sometimes the outer and inner surfaces of the bag can be infested with insects which should be collected and labeled accordingly. Insects that are found on the inside of the body bag may have crawled from the body due to temperature changes. If the remains have been refrigerated prior to the autopsy, the forensic entomologist must record the following: temperature of the chamber, the total time the body was cooling, temperature changes dealing with the transfer of the body to the morgue, and the temperature of the maggot mass when the body is removed from the cooler. Clothing should also be carefully examined for insects. Moist areas on clothing are good places to look for fly eggs (99).

Areas of the body where there is concentrated insect activity should be photographed in order to keep a record of the insect composition and infested area. Collection should also take place at greatly infested areas. On a fresh corpse, the face is the most likely area to have insect colonization. Also, genital and rectal areas should be checked as they attract ovipositing flies. The hair line must be examined for the presence of lice eggs as well as fleas, ticks, and mites. Eyelashes and eyebrows should also be examined as they can be homes for follicle mites (100).^[3]

Analysis of the Body

Clothing

Different types of insects are found on carrion depending on the location. Entomologists give a detailed examination of clothing if found on the carrion. Examination of the clothing is important due to the different types of insects and stages of insects that may be present such as eggs, larvae, pupae, or even adults. Entomologists examine the clothing carefully, such as looking through the folding of shirts, pants, socks, etc. Fly eggs are often found in moist areas such as nostrils, eyes, and mouths. This is due to the attraction of moisture and shelter, which is also used for deposition on these specific body parts.^[4]

Buried Corpse

Remains that are buried carry different types of insects as mentioned above. Due to lower, constant temperatures at different depths of the soil, the decomposition process is slower for burials as to a corpse being found out on a hot summer day. Blowflies, for example, are usually the first insects to reach a corpse. They often fly from their birth place to the corpse to feed. Entomologists might find flesh flies and muscidae larvae on the corpse. Coffin flies or Scuttle flies can also be found in this type of setting.^[5]

Study in Paramo, Colombia

In Paramo, Colombia it is said that the minimum post mortem interval could be estimated by the knowledge of the pattern of insect succession on a corpse. This is due to the different types of insects that develop in different types of regions due to weather. Different types of insects assist in determining the five stages of decomposition. Calliphora nigribasis was found at the fresh stage and Compsomylops verena was usually found at the bloated stage. Compsomylops boliviana can be found at the active decaying stage and Stearibia nigriceps and Hydrotaea sp. can be seen during the advanced decay. Finally, Leptocera species usually arrive for the dry remains of the body.^[6]

Interpreting the Weather

Interpreting the recorded weather data is an important feature to a forensic entomologist’s success. Weather samples include temperature and conditions for that particular day and two weeks prior. All weather data must come from a credited national weather service. Any faults in their report can negate a court case. A forensic entomologist must record ambient air temperature, ground temperature (if a body was buried), and maximum/minimum air temperature for three to five days after the crime/event and approximately two weeks before the incident. This information allows for calculation of Accumulated Degree Days (ADD). Accumulated degree days are based on weather temperature, these recordings can help predict when a developmental stage will be reached based on heat requirement. Accumulated Degree Day Formula: (Average Temperature-Minimum threshold) x [unit of time])^[7]

'Weather Technology'

Conditions such as rainfall or any extreme weather condition come into play. All these factors can prove or disprove how long the body was there according to the insects found. Many insects live in certain habitats, these play a vital role in an entomologist’s job. These investigators must know

• what insects lived in or around the area.

• what insects on the body are not local to the area.

The entomologist needs to understand weather and weather patterns in order to give a professional and accurate report. New technology in meteorology has allowed for vast improvements in forensics. HailTrax gives an accurate estimation of where hail has fallen. HailTrax also determines hail size within an area. This information can prove to be helpful for a forensic entomologist when hail was possibly a factor in the case.^[8]

Education

Undergraduate Level

The education needed to become a forensic entomologist is extremely thorough due to the expertise needed to actually practice the discipline. At the undergraduate level, most prospective students major in Entomology. This is the most traveled route into the field of forensics. However, other avenues do exist. Another frequently encountered major is Forensic Science. Students majoring in this would still need to have other entomological education. This ensures that basic concepts of the entomological field are instilled in future entomologists.^[9] There are also several classes of utmost importance to the aspiring forensic entomologists as discussed by accredited entomologists. These include, but are not limited to: Biology, Chemistry, Genetics, Taxonomy, Medical entomology, Biochemistry, Forensic Law, Parasitology, and general entomology. It is believed that students with a thorough knowledge of these courses have prepared themselves well for higher study.^[10][11][12] Just as in preparation for other graduate school programs, experience can help boost your resume. Shadowing, or working with professionals who know the field can be rewarding and help prospective students gain valuable insight as to knowing if this field is for them. Summer internships and performing research or lab work in entomology are two ways entomologists suggest that undergraduates can become more prepared for their future work.^[10][12] The main focus for undergraduates needs to be on courses, grades, and experience.

Graduate Level in the USA

There are about sixty-two total scientists involved in the field of forensic entomology. Fifty-three percent are solely involved in the “medico legal” branch, the branch that involves insects and violent crimes. Eight percent say that this branch of entomology is one of their specialties. Of the total, most are also affiliated with colleges such as Texas A&M University and Michigan State University where entomology courses are taught and research conducted (Professional Status of Entomologists). Getting to this point as a newly graduated college student can seem a daunting task. It is essential that one get a degree beyond a bachelor of science (BS). However, currently there are no graduate programs designed specifically for forensic entomology. Senior Academic Advisor for the Department of Entomology at Texas A&M University, Rebecca Hapes, made it very clear that individual graduate students in entomology can focus their research on some aspect of forensic entomology, but there is no exclusive program. Most of the entomologists considered to be professional hold a PhD, an MS, or MD in entomology or related fields (Professional Status of Forensic Entomologists). It is also important to note that there is no certification test to test the merit of aspiring forensic entomologists. Dr. Jeffrey Tomberlin, a professor at Texas A&M University with a PhD in Entomology says that the “sole exam available to date is through the American Board of Forensic Entomology”^[11] which is further restricted to only those with at least a MS degree. One of the major reasons for this may be attributed to the fact that few entomologists worldwide are employed as full-time medico legal experts (Professional Status of Forensic Entomologists). Most, as mentioned earlier, lend their knowledge and expertise to universities, police agencies, and the legal system when they can (What Is A Forensic Entomologist). It is important to realize that a forensic entomologist can gain support by constantly staying abreast of new ideas that emerge in the field and spending large amounts of time working and conducting research to broaden our scope of how insects can affect our life.

Forensic Entomologists in the USA today

There are several different occupations for forensic entomologists since the field itself is still so very young. Many state universities employ a number of entomologists to teach. Dr. Jeffery Tomberlin (former president of the North American Forensic Entomology Association) is an assistant professor for Texas A&M University's entomology department. His responsibilities as an instructor include teaching, maintaining a research program, advising, and working with students who have an interest in working in the field of forensics. Dr. Tomberlin says that, in his spare time, he works with law enforcement agencies and conducts workshops to teach detectives, crime scene investigators, and others on the use of insects in crime scene investigation (CSI). He serves as a consultant in forensic investigations and can even be called upon at times to investigate the presence of insect evidence at crime scenes to determine PMI as discussed earlier. Dr. Tomberlin is most proud of his work with Dr. John Wallace (of Millersville University) in initiating the first conference on forensic entomology to be held in North America. First held in Las Vegas, Nevada, about 50 people registered for the conference which is now in its 6th year and has paved the way for the development of the North American Forensic Entomology Association. The conference has since gone from an annual meeting to the formation of an official society for those interested in the field of forensics. He had the luxury to serve as the NAFEA's first president and was later succeeded by Dr. Wallace.

Although he’s been working in the field for a number of years and has experienced the surge of new developments and advances within forensic entomology, Dr. Tomberlin believes that there is still a great deal more progress to be made in the near future. The urban and stored product entomology arenas are the areas, in his opinion, with the most potential for growth since they both impact the majority of the country in a way much closer to home. He also hopes for more recognition of these two areas and their contribution to the field of entomology. The wide variety of experiences and opportunities for employment help to make forensic entomology among the most diverse careers to have developed among the scientific professions and it looks as though at this rate it will continue to be for a number of years.

A fellow educator and member of the NAFEA, Dr. M. Eric Benbow, currently Assistant Professor of Entomology at Michigan State University, provided his own perspective on his career as well. Dr. Benbow's own line of work involves his giving seminars and lectures that have to do with forensic entomology, routinely doing research involving both case and laboratory experiments, and serving on graduate student committees. Previously, he has done research that has involved understanding life history characteristics, larval growth rates, and the environmental factors that influence both. When asked if there was anything in his career of which he was especially proud, Dr. Benbow's response was rather sentimental. The first accomplishment he shared was his writing of a $2 million grant to study the ecology of an infectious disease and his role as an expert witness for a contested case hearing for surface water issues in the Hawaiian Islands. Second on his list of accomplishments was his writing of numerous letters of support and recommendation for students that have gone on to graduate, medical, and law school. Dr. Benbow's pride in his ability to impact the lives of his students becomes obvious when he later stated that being able to interact with students and having the freedom to pursue research that interests him is the most enjoyable part of his job.

Forensic Entomologists' roles in academic settings provides them with opportunities to exploit their passions for teaching, discovery, and invention. Many spend their careers making great contributions to their field, colleagues, and a number of students fortunate to have such dedicated instructors. It is this commitment to continuing the education of their students that not only proves rewarding for these teachers, but also ensures that there will be others to take over their line of work in the still developing future of forensic entomology.

Famous Entomological Cases

These cases illustrate the importance of the education, training, and job expertise needed to gain the necessary skills needed in forensic entomology.

First Recorded Entomological Case

The first written record of forensic entomology being employed in legal matters dates back centuries to Song Ci (1186-1249) a Chinese forensic medical expert.^[13] Song Ci served as a judge on the Chinese high courts and wrote ‘’Collected Cases of Injustice Rectified’’ in 1248. His book was a summary of several accounts of his own experiences with forensic cases and his personal reflections upon justice.^[14] One case in particular relates to the use of forensic entomology to solve a homicide. A man was murdered after suffering several sickle-shaped slash wounds. Since there was no evidence to be found at the scene of the crime, the judge in charge of the autopsy decided to conduct an investigation. The judge found that the victim had recently been involved in an argument with another man concerning loan money that the victim wanted paid. The judge was able to track down the whereabouts of the suspect along with other evidence. He then issued an area wide confiscation of all the sickles, stating that any man unwilling to comply would be charged with obstruction of justice. Between seventy to eighty sickles were turned in during the investigation in the summer heat. As the sickles lay out in the sun, flies were attracted to the sickle whose owner just happened to be the man involved in the loan disagreement. The man was later taken into custody and interrogated but would not confess. The judge told the suspect to look at the evidence: the flies were attracted to the remnants of blood on his sickle. This was enough to charge the man with the victim’s murder. Song Ci believed in the importance of irrefutable evidence and was strongly opposed to wrongful conviction. As a judge, Song Ci knew that investigations and autopsies needed to be performed under careful scrutiny and stringent protocol to protect the innocent from being unjustly accused.

Danielle Van Dam Murder Trial

A more recent and widely publicized homicide case that employed the use of forensic entomology was the David Westerfield trial. Westerfield was convicted and sentenced to death for the kidnapping and murder of seven-year-old Danielle Van Dam in 2002.^[15] Van Dam went missing from her home on the night of February 1, 2002, when her parents thought she was asleep in her bed. After weeks of search efforts, on February 27, 2002, the naked, decomposing body of the seven-year-old was found on the side of a road. Defendant David Westerfield, who was a neighbor to the Van Dam family in Sabre Springs, California, became a suspect when he was away that weekend, leaving around 9:30 a.m. the morning Danielle went missing.^[16][17] Westerfield had also been spotted at a local dry cleaners dropping off two comforters, two pillowcases, and a jacket. These articles were later examined, and a small stain on the jacket tested positive for the blood of the victim.^[18][19] Once Westerfield was placed under surveillance, the police recovered carpet fibers and a handprint in his RV, and hairs in his house and RV, that were similar to those of Danielle. Suspected child pornography was also found on his computer.^[20] On June 4, 2002, the murder trial began; Westerfield pleaded not guilty. The defense suggested that due to their lifestyle (swinging, marijuana smoking, alcohol abuse and propositioning strangers), her parents had put Danielle in danger by being around seedy and untrustworthy people who could have kidnapped her.^[21][22][23] The defense lawyers also alleged that the child pornography was downloaded by the son of the accused and pointed out the lack of investigation into searching for other suspects. The prosecution called into evidence the fiber, hair, fingerprint, and blood analysis to support their case. Expert witnesses were able to link fibers found on the body of the victim to the home of the accused.

Entomology, however, played the star role in the murder trial. The police had invited David Faulkner, the local forensic entomologist, to attend the autopsy, where he collected the insects from Danielle’s remains. After examining the maggots, he stated that they began growing ten to twelve days prior to the autopsy (so February 16 to 18).^[24][25][26] This discovery did not match up with the prosecution, since insects normally infest a body within minutes or hours, and Westerfield was under surveillance during this time (from the night of the 4th), and so could not have dumped the body.^[27] Faulkner was therefore hired instead by the defense as their expert witness. Dr. Neal Haskell also testified for the defense, stating that initial colonization occurred between February 12 and February 21.^[28] The prosecution called in Dr. Madison Lee Goff, who estimated that initial insect infestation occurred February 9 to February 14.^[29] The defense then called Dr. Robert Hall, who believed the body of the victim was initially infested between February 12 and February 23.^[30] Hall was heavily interrogated as to his method for figuring the post-mortem interval and important weather factors.

The entomology therefore pointed strongly to the body only being accessed by insects in the middle of the month, so the prosecution argued that there was a delay in infestation. For example, a body covering, such as a blanket, might have kept flies at bay initially. But no covering was found, and Goff said the longest delay by such a shroud was two-and-a-half days.^[31][32] Goff and forensic anthropologist Dr. William Rodriguez said ants and coyotes might have eaten the first waves of fly eggs or larvae on Danielle’s body, making it appear the body was exposed for a shorter time. But flies lay batches of hundreds of eggs, and Hall said they might attack some of the larvae, but he didn't think they would be able to completely wipe away remnants of a first wave.^[33][34] This was the driest year in San Diego in more than a century, as a result of which the fly population was the lowest Faulkner had ever seen. But Hall said insects are “extremely resilient” to drought, Faulkner said flies were still present, and Haskell said the insect life recovered from the body proved flies were still abundant at the scene.^[35][36][37] There were only a couple of maggots in her head, even though bugs are usually drawn first to the head. But that could be because the body was naked, so the pelvic openings were immediately available, and in any case the Medical Examiner didn’t think it unusual to have the brain still intact.^[38][39][40] It was suggested that bleach on the body might repel insects. Haskell didn’t know, but experiments with muriatic acid, which is much more powerful, had only delayed egg laying by two to three days.^[41]

The main prosecution argument was that the body was rapidly mummified by the hot, dry weather: the surface became a hard case making it inhospitable to insects until it was opened by scavengers, which could have been several days later. But the first Santa Ana wind only began on the 7th, and Hall said flies could be attracted to bodies that were mummified on the outside.^[42][43][44] Goff and Rodriguez argued that the small size of the body - 58 pounds - was partly responsible for the rapid mummification, but the pigs used in Goff’s studies were even smaller.^[31] Prosecutors also suggested that the body might have been kept for 24 to 36 hours in a storage compartment in the motor home before it was dumped, and this contributed to the mummification. But Haskell said such a scenario could have kept her body from being colonized by insects, but it also would have accelerated her decomposition and made her more attractive to blow flies.^[45][46]

In the end, the jury found Westerfield guilty of kidnapping and first degree murder.

Black Bear Poaching

Forensic entomology is not only applicable in homicide cases, but also in other legal matters. The next case discusses the use of forensic entomology in an illegal poaching case. In July 1995, two baby black bears were found shot to death close to Winnipeg, Canada.^[47] Both the bears had their gall bladders removed, most likely to be sold and used as medicine in Asia. Witnesses heard gun shots and spotted a vehicle. Two men were found hiding near the bear’s bodies and witnesses were able to confirm the suspects belonged to the vehicle that was sighted earlier. The witnesses recollections were a helpful lead, police officers could not hold the two men solely on suspicion. More evidence was needed in order to connect the two suspects to the crime. Blowfly eggs were found and collected from the bear bodies and sent to entomologist Gail Anderson. Anderson, as an experienced entomologist, knew that blowfly eggs take twenty-two hours to hatch in the hot summer temperatures the bears were found in. By counting back twenty-two hours and taking into account the weather data for the time the bears were discovered, she was able to find when the fly eggs were first deposited on the bodies. The time that Anderson had found showed that the eggs matched up with the time the two suspects were discovered near the scene of the crime, heard the gun shots, and saw their vehicle.

Conclusion

Forensic entomologists experience a wide variety of opportunities to use their expertise whether in the classroom, the research lab, or in the field. There is an extensive amount of time and energy put into learning the trade, but the job is rewarding in that it gives forensic entomologists the opportunity to impact both the science and social community with ground-breaking research that reaches as far as into the home. While the practice of studying insects has existed for centuries, there are so many areas of the field that remain largely untapped and promising. The new ideas of forensic entomologists will continue to emerge over the coming years.

See also

• Use of DNA in forensic entomology
• List of schools and organizations related to forensic entomology
• Forensic entomology
• Forensic entomology and the law

References

Sources

• Brundage, Adrienne. “Collection, Preservation, and Rearing of Dipteran Samples”. Forensic Entomology Class Lecture. Texas A&M University, College Station. 27 Feb. 2008.
• Brundage, Adrienne. “Entomology”. Forensic Entomology Class Lecture. Texas A&M University, College Station. 25 Jan. 2008.
• Catts, E. Paul and Neal Haskell. “Entomology and Death – A Procedural Guide”. South Carolina: Joyce’s Print Shop, Inc, 2005.
• Chang, Maria L. “Fly Witness. (forensic entomologist Gail Anderson helped authorities convict two poachers of baby black bears by studying blowfly eggs) 1 Oct. 1997.
• A ‘little girl lost’ is found dead, allegedly killed by neighbor. 3 June 2002. Court TV News. 28 Feb. 2008.
• When Was Danielle Van Dam Killed? 2007. Court TV News. 28 Feb. 2008.
• Forensic and Investigative Sciences (FIVS) Major Curriculum. Department of Entomology. 20 Feb. 2008. Texas A&M University. 22 Feb. 2008
• Hapes, Rebecca. Personal Interview. 27 Feb. 2008.
• Kim, Ke Chung, PhD., Dipl.-ABFE. E-mail Interview. 15 Feb. 2008.
• Merritt, Richard W., PhD., D-ABFE. E-mail Interview. 15 Feb. 2008.
• Professional Status of Forensic Entomologists. American Board of Forensic Entomology. 2004. University of Missouri. 22 Feb. 2008.
• Ryan, Harriet. Bugs: The best witnesses? Trial Report. 18 July 2002. Court TV News. 28 Feb. 2000.
• “What is Forensic Science?” The Tech FAQ. 28 Feb. 2008.
• Tomberlin, Jeffery K., PhD, D-ABFE, F-AAFS. E-mail Interview. 15 Feb. 2008.
• “What is A Forensic Entomologists?” Frequently Asked Questions. Forensic Science Master’s Program. 2008. Michigan State University. 22 Feb. 2008.