Entomology

1. AnthropologyForensic Anthropology is the study of bones or other human remains. The forensic anthropologist can determine if bones/body parts are human or non-human, how long they have been there, the cause and manner of death, the age, the "race", the sex and the physical characteristics of an individual. All of this can be done by careful examination of the remaining bones, tissue and other items that may be found at the crime scene. The leaves under a body or the pollen on the clothes may indicate that a body was buried at a certain time of year. If the pollen is from a distant area, the type of pollen may be important to investigators. Forensic science also uses anthropology to determine the cause of death from remains. The remains may be severely degraded leaving only a few bones. The forensic anthropologist and his/her team must be very careful in collecting any remains, as even the smallest bone fragment may show the cause of death. For example, if a rib bone is chipped and the pattern on the bone matches the toolmarks of a suspect's knife, this evidence may be incriminating. Entomology Forensic entomologists study insect life on or near bodies to determine the time and/or date of death. Only a few hours after death, flies and other insects are attracted to bodies and begin to lay eggs in the ears, eyes, nose, mouth or open wounds. Within days or hours, these eggs quickly grow into different stages of their life cycle (called instars). Different species of flies grow at different rates. The entomologist will take samples of the insect larvae and cultivate them to verify what species they are. Before the entomologist takes them he/she will determine the stage in their life cycle of the maggots or flies. Once he/she knows the species, and given the stage of their life at which they were found, the entomologist can determine how many hours/days the body has been exposed. The insect life that will appear on the body varies with the season, surroundings (i.e. geographical location) and other factors. Fingerprint Examination A fingerprint is a mark left behind after the ridges on the fingers, hands, toes or feet touch an object. There are two types of prints: a direct fingerprint (it creates an impression) and a latent print (dirt, sweat or other residue that is pressed onto another object). Fingerprints have three main classes: the arch, whorl and loop. Within these three classes, there are an immense number of patterns that are different for each one of us. Aside from scars, there are forks, islands or spaces where the lines of a fingerprint make different latent prints. No two fingerprints are the same. Fingerprints can be taken even from surfaces which are not smooth (e.g. clothing or paper towel). Even if fingerprints are months or years old, new technology allows scientists to recover fingerprints from objects. Techniques using charged particles or particles that glow under certain conditions are applied to test areas. This allows for testing of larger areas and faster processing of fingerprints at the crime scene.

2. FirearmsIn any case where a firearm has been used, there are many clues that are left behind. An investigator might find a piece of the bullet (fragment), a casing, the whole weapon, bullet holes or GSR (Gunshot Residue). All of these clues can be used to match a suspect weapon with the scene of a crime. Here's how... Bullet fragments may contain markings that were imprinted by passing through the barrel. Even though each barrel may be made the same way, differences in the metal (and wear) will result in unique patterns on a bullet that passes through the barrel. Barrel Cross SectionEach barrel has different lands and grooves. The "lands" are the raised parts inside the barrel, and the "grooves" are the recessed portion. The number of lands and grooves, their size and shape, may assist in determining the make and the type of weapon that was used. Lands & Grooves When each barrel is produced, there are differences that are unnoticeable to the human eye which may only appear under a microscope. The marks left on the projectile (bullet) are from the lands and grooves as well as finer scratches that have resulted from use or production. Weapon Barrels In Production No two barrels will give the exact same markings on a bullet (like a fingerprint). The Firearms Specialist may take the weapon in question and fire it into water and retrieve the test bullet. The test bullet is then compared to the fragment using a comparison microscope. If it is a match, a photograph may be taken for use as evidence in court. Bullet Fragment Casings contain information about the type of ammunition, stamped onto the base of the cartridge. But there is more information hidden on the casing. Parts of the firearm which come in contact with the casing may leave markings. Just like the marks left behind from the lands and grooves, these are unique and can be compared to the suspect weapon. Test Firing Gunshot residue (GSR) is a fine powdery substance that results from the discharge of a cartridge. When a weapon is fired this residue spreads all over, and can be found using methods at the forensic laboratories. These tiny particles settle like dust over the victim, shooter and environment. Some of the particles are blasted into the target area as well. GSR includes particles from the primer, the casing itself and from the bullet in addition to "the combustion of the gun powder." Odontology Teeth are the hardest substances in the body. Long after the flesh, organs and even bone have been degraded, teeth may still give clues as to the identity of an individual. Dental remains can still be used for identification after one and a half hours at almost 1,000 degrees celcius, or after 5 days inside a shark's stomach! Dental records from the victim's dentist office may be compared for identification. Hospital records, molds for dentures or photographs may also be used for matching. Methods used for identification include photographs, radiographs (X-rays), dental charting, dental impressions, preservation of oral structures (i.e. dentures or braces), jaw articulation and occlusal analysis and DNA analysis. Dentures, for example, may contain mold numbers on the back of the denture teeth that can assist in identification. Children may not have any dental records, but they may have misshapen teeth. Under the age of five years, it is often difficult to find dental records of children. However, DNA samples may be of great use. The number of adult/juvenile teeth that have penetrated the skin (erupted) can also serve as a rough guide to the age of a person. The amount of mineral build up on the teeth is another method used to determine age. Bite marks may be compared to dental impressions, photographs, traces and models. Even if bite marks are not matched to an individual, the saliva left behind on a bite mark may be used for DNA analysis to find the identity of the perpetrator. Remains from mass graves or aircraft wreckage sites may require identification from the forensic odontologist. It is often the case where bones and teeth are mixed together, complicating the identification of human remains. Here, several methods and a team of forensic odontologists may serve to identify the remains. Bullet in Flight. The GSR can be found on clothing, furniture and even on the suspect! The suspect will have adhesive lifts applied to his or her hands and these will be sent to the lab. At the laboratory, the lifts will be checked for GSR. The chemistry section use a S.E.M. (Scanning Electron Microscope) to see the particles which are very small. You can see the GSR on the tip of a pin! Gun Powder ResidueThese small particles may be caught in the suspect's hair or clothes or may even be brushed off onto other objects (like a car seat).

3. Trace EvidenceTrace evidence are items found in small amounts that can be analyzed. They may include such items as hair, fibre, glass, metal, paper, paint or botanical sources (e.g. soil, pollen, leaves). Paint Chip Paint can be liquid, chip or smears. Paint can be identified by color, type, texture (glossiness, granularity, hardness, wrinkling, cracking, blistering and chalking properties), layer structure and composition. Once the information is gathered, it can be compared to databases where information is stored about many other types of paint. This way, one can find out details about the clues that have been found. Paint identification can be very useful for hit and run incidents. The victim and the crime scene may have small chips of paint left behind from the assailant's vehicle that can be taken into evidence. At the lab, the characteristics of the paint are noted and then entered into a database. The databases allow for comparisons of large amounts of data. A match of vehicle paint from the crime scene to that in the database may yield the make, model and year of the car in question which assists the investigating officer as well as the courts during the investigation. Gunshot Residue Particle on Top of Hair Hair: Comparison microscopes are used to see if a hair sample found at a scene matches a known sample. Examination of hair can also determine the animal family of origin, the body area of origin for human hairs and the method of removal from the body, as well as providing an indication of racial origin. Scalp hair can give the scientist the most information because it usually undergoes the most varied treatments (dying, curling, cutting, hairspray, etc...). Magnified Hair Sample Hair comparison is not conclusive and this is the reason why DNA methods may also be used. Since all nucleated cells in the body contain DNA, hair roots and roots sheaths may be used, and the amount of DNA may be amplified using a method called PCR. The DNA is then typed and a match may be found. The first 10 mm of the bottom of each hair may be used for the DNA testing because it contains the root sheath. Although it does not contain nuclear DNA, the hair shaft may be analyzed for mitochondrial DNA. Pathology When a human dies, the body shuts down in stages. The time of somatic death is the time pathologists are interested in. Somatic death is the time that the body as a whole stops functioning. Cellular death comes later, this is the time where the cells stop functioning. Hypostasis occurs after the heart stops pumping blood, and the blood goes to the lower parts of the body (due to gravity). It is at this time where body parts become a bluish or pale colour. The external temperature lowers during hypostasis, but it does not assist in determining the time of death. Autopsies are normally performed by local hospital pathologists. Determining the time of death based on temperature depends mainly on the environment of the body. Upon death, the core temperature remains at approximately 37 degrees Celsius for one to two hours, then drops 1 to 1.5 degrees per hour. However, this depends on many factors such as bacterial infection of the deceased, hypothermia, or other temperature affecting conditions. If there is a high temperature in the surrounding area (e.g. turning up the heat in a room), the time of death as determined by core temperature may appear more recent than it actually was.