Forensic Entomology Notes PDF

Forensic Entomolgy TR TR TR TR Bugs and Death  Introduction to Entomology Entomology the study of insects Forensic Entomology the study of the application of insects in criminal investigations The first recorded case of the use of insect evidence was the case o...

Forensic Entomolgy TR TR TR TR Bugs and Death  Introduction to Entomology Entomology the study of insects Forensic Entomology the study of the application of insects in criminal investigations The first recorded case of the use of insect evidence was the case of Sung Tzu in China in 1235 A victim was murdered with a sickle and the lawyer Sung Tzu ordered the men to lay down their sickles Flies congregated on one sickle and Sung Tzu questioned the owner, who confessed to the murder  Case Study: Jigsaw Murders Buck Ruxton lived with his wife, Isabella Kerr, and their housemaid, Mary Rogerson, and three children He was a trained physician In late September 1935, the bodies of Isabella and Mary were found in a ravine in Scotland Their bodies were wrapped in a newspaper dated September 15, 1935 Buck Ruxton Maggots on the bodies were analyzed and found to be between 12- 14 days old They were last seen alive on September 14, 1935 Police searched the house and found blood in the bathroom Buck Ruxton was found guilty and hung on May 12, 1936  Introduction to Insects Insect A type of invertebrate animal having an exoskeleton with six legs Insects are the most common group of animals and make up more than half of all living organisms They are found in nearly all environments on land and in the ocean Even in Antarctica and the Arctic Circle Insects almost always hatch from eggs and go through several stages of growth, usually molting from one exoskeleton to another  Insect Anatomy The bodies of insects are broken down into three segments: Head Brain 2 antennas Eyes Mouth Thorax 3 pairs of legs Wings, if they fly Abdomen Digestive system Reproductive system  Insect Spotlight: Blowfly The blowfly is known as Calliphoridae, with 1,900 different species around the world Blowflies are commonly shiny with metallic coloring Green, blue or black thoraces and abdomens Blowflies can smell dead animals (carrion) up to 1 mile away and will lay eggs on it Eggs will hatch into larvae, which are also known as maggots The rate at which blowflies grow and develop is highly dependent on temperature and species  Metamorphosis Metamorphosis Biological process by which an animal develops from hatching, involving an abrupt change in the animal’s body structure The four stages of blowfly metamorphosis: Eggs Laid on a carcass and then eggs hatch ~24 hours later Larvae (maggots) 1st instar Up to 5 mm long, shed exoskeleton at end of stage, takes 1-2 days 2nd instar 5 to 10 mm long, shed exoskeleton at end of stage, takes ~2.5 days 3rd instar 15 to 20 mm long, takes 4-5 days, then enter the ground Pupa Brown stage which emerges from ground in 6-8 days as adult fly Adult Blowflies Takes 14-16 days from eggs laid until adult blowfly  Postmortem Time Interval Postmortem Interval (PMI) the time between death and the discovery of the body After 72 hours, the body leaves rigor mortis and begins to decompose (Bloating), which makes it much harder to determine PMI Insects help to determine a more accurate time of death They hatch and grow in specific intervals Entomologists can create a timeline of decomposition The more variety of insects, in great numbers, allows a more accurate Postmortem Interval The most common insects involved in decomposition: Blowflies Beetle species Beetles  Insect Spotlight: Carrion Beetle The carrion beetle is a relatively small family of beetles, with only 200 species worldwide Carrion beetles feed on carrion as their name implies They bury underneath a carcass They also bury their food (carrion) under the ground Their metamorphosis occurs at a slow rate: Eggs hatch 2 to 7 days after being laid The three instar stages last 10 to 30 days Pupation takes 14 to 21 days Carrion beetle Adults take 26 to 58 days to completely come from an egg  Fresh Stage Decomposition & Insects Fresh stage decomposition starts immediately after death and continues until the animal starts to bloat No odor is present Scorpionflies Scorpionflies will only be present in fresh stage decomposition and not in any other stage The Blowfly will arrive within minutes to hours and deposit House fly eggs, which will hatch within 24 hours Flesh flies and house flies are also very common Ants may also be seen feeding on the carcass, the eggs and any larvae that has hatched Flesh fly  Bloated Stage Decomposition & Insects Bloat stage decomposition begins with bloating in the Cheese fly stomach and the skin changes colors The odor of putrefaction becomes very noticeable Blowflies are present in large numbers with maggots of Fanniidae various sizes fly Flesh flies and house flies are also still present Cheese flies and Fanniidae flies arrive Beetles arrive with rove beetles, carrion beetles and Checkered Beetles checkered beetles feeding on fly eggs and maggots Hister beetles may be found under the carcass  Insect Spotlight: Hister Beetle The hister beetle is also known as a clown beetle There are 3,900 hister beetle species worldwide They range in color of shiny black or metallic green Hister beetles are highly predatory nocturnal beetles and will even eat each other The adults commonly eat egg, larvae and adults Especially flies Their larvae will eat carrion Different species of beetles arrive at different Hister beetle intervals during decomposition  Active Decay Stage Decomposition & Insects The beginning of the active decay starts with the feeding maggots piercing the skin so internal gases release The carcass deflates The carcass strongly smells Blowflies are the most common insect and maggots are Active Decay concentrated in orifices, then move towards the chest and stomach Black scavenger flies first arrive during active decay Beetles become the dominant insect, especially with rove beetles and hister beetles feeding on other insects Black scavenger fly  Advanced & Dry Decay Stage Decomposition Advanced Decay Advanced decay is marked by the mass migration of third instar maggots of the blowfly and adult blowflies start to leave They burrow in the ground to pupate before emerging as adult flies Cheese fly larvae are also present Skin Beetles Adult skin beetles arrive but no larvae are present Dry Decay The dry decay stage is mostly skeletal remains with dried skin Adult cheese flies emerge from pupation Woodlice Skin beetles leave Centipedes, millipedes, woodlice, snails and cockroaches are commonly seen near dry remains Millipede  Factors Affecting Insect Activity There are many factors which impact insect activity Speeds up insect activity: High humidity Higher temperature Slows down insect activity: Colder temperatures Large amounts of rain Hanging body In bodies of water Flies will not fly across large distances over water  Drug Use & Insects Entomotoxicology A new branch of forensic science which analyzes toxins in insects which aid in decomposition Mainly blowflies and beetles Investigators can determine whether toxins were present in the body at the time of death by the altered cycle of metamorphosis in insects For example, in blowflies: Heroin speeds up larvae stage but slows down pupation Cocaine and methamphetamine speed up the rate Barbiturates increase the length of the larvae stage, and thus overall time Morphine slows down the rate of metamorphosis  Career Spotlight: Forensic Entomologist Forensic Entomologist Forensic scientists who specializes in entomology Forensic entomologists study insects at crime scenes to get an estimated Postmortem Interval Compared to many other fields in forensics, the forensic entomologists require a doctorate degree After graduating high school, students will earn a Bachelor’s degree, then a Masters and PhD It will take an average of 7-9 years The annual salary ranges from $40,000-$100,000  Training Spotlight: Body Farm Body Farm Research facility used to study human decomposition A body farm is a training facility, for students, police, and teachers, to study human decomposition The facility sets up different experiments to study decomposition under fixed conditions There are two body farms located in Texas: Sam Houston State University Huntsville, Texas Texas State University San Marcos, Texas  Case Study: Vincent Brothers In 2004, the wife, mother-in-law and 3 children of Vincent Brothers were killed in California The husband and father, Vincent Brothers, stated he was visiting family in Ohio during the murders so couldn’t have done it Detectives did not believe his story and got a search warrant for his rental vehicle in Ohio Forensic entomologists evaluated his radiator and air filter The insects found were only found west of the Rocky Mountains and could Vincent Brothers not have only come from Ohio Investigators theorized he drove the rental car from Ohio to California and back after committing the murders In 2007, Vincent Brothers got the death penalty for the five murders He remains on death row as of 2022 Earnestine & Joanie  How to Collect Insects Collecting insects requires special equipment at the scene: Insect net 70% ethanol or rubbing alcohol solution Mix 1:1 with water Glass vials Forceps Collect flying insects near the body with an insect net and place immediately in the glass vial with the 1:1 solution Collect crawling insects near wounds or body opening using forceps and place immediately into the glass vial 1:1 solution DO NOT probe wounds or open areas of the body Insect net  Collecting Maggots Collecting maggots requires special procedures compared to other insects: Record the temperature of the maggot mass Record the air & surface temperature at body level of the victim Collect the largest maggots seen from several sites around the body Immediately place in glass vial with 1:1 solution Collect 15-30 maggots and place in a breathable container with lid The container should have potting soil with a piece of liver Place a wet paper towel over the liver with maggots Mark the container with date, time, part of body collected, investigator’s initials DO NOT mix different live species of insects as some are predatory In addition, collect soil samples around the body up to 3 feet away Scoop soil samples into a locking plastic bag and chill it Transport all specimens to a forensic entomologist as soon as possible  Documentation of Entomological Evidence It is absolutely vital to record all climatic conditions of the area for at least two weeks preceding the body discovery Record: Minimum temperature Maximum temperature Amount of precipitation Wind speed Wind direction Relative humidity Cloud cover