Forensic Entomology Notes PDF

Name: [ ] Date: [ ] Per: [ ] **Forensic Entomology Notes** **Introduction to Entomology** - **Entomology** - the study of insects - **Forensic Entomology** - the study of the application of insects in criminal investigations - The first recorded...

Name: [ ] Date: [ ] Per: [ ] **Forensic Entomology Notes** **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 - 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*) - **1^st^ instar** - Up to 5 mm long, shed exoskeleton at end of stage, takes 1-2 days - **2^nd^ instar** - 5 to 10 mm long, shed exoskeleton at end of stage, takes \~2.5 days - **3^rd^ 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, 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* - *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* - *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** will only be present in fresh stage decomposition and not in any other stage - The **Blowfly** will arrive within minutes to hours and deposit 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 **Bloated Stage Decomposition & Insects** - Bloat stage decomposition begins with bloating in the stomach and the skin changes colors - The odor of putrefaction becomes very noticeable - **Blowflies** are present in large numbers with maggots of various sizes - **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** 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 intervals during decomposition **Active 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 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 **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 - 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 - **Skin beetles** leave - **Centipedes, millipedes, woodlice, snails** and **cockroaches** are commonly seen near dry remains **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 - Unable to bury under body and air dries it out faster - 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 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 **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 **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*