Forensic Entomology Quiz

Classifying Evidence

• Direct evidence establishes a fact, like eyewitness accounts or confessions. Nothing else is needed.
• Circumstantial evidence requires a judge or jury to make an inference about what happened. Examples include fingerprints or hair matching a suspect at a crime scene. This links the suspect to the scene.
• Circumstantial evidence is often more reliable than eyewitness accounts, which are frequently inaccurate.
• Eyewitnesses are notoriously poor at identifying suspects or recalling events, often misinterpreting what they saw.
• Fingerprint and DNA evidence are usually far more accurate in identifying individuals than eyewitness accounts.

The Damilola Taylor Case

• Damilola Taylor, a ten-year-old boy, was stabbed to death on November 27, 2000.
• A teenage girl provided crucial evidence, claiming she witnessed the crime.
• The offer of a £50,000 reward influenced her testimony.
• The police inquiry focused on four youths, but investigations led to the criminal convictions of two brothers.

Further Evidence Classification

• Physical evidence includes non-living/inorganic items like explosives, shoe prints, tool marks, fibers, paint, glass, and documents.
• Biological evidence includes organic items like blood, saliva, urine, semen, hair, plants, and insects, and can be used to link a suspect to a crime scene or identify an individual.

How Else Can We Classify Evidence?

• Reconstructive evidence: allows investigators to gain an understanding of the actions that occurred at the scene. This is useful in crime scene reconstruction.
• Examples include broken glass, footwear marks, and blood spatters.
• Associative evidence: connects a suspect to a crime scene or elsewhere. Examples include fingerprints, footwear marks, or blood spatter from a source of origin.

Hair, Fibres, and Glass

• Hair analysis: (DNA in follicle) can be used to determine individual characteristics. DNA is used to determine if hair matches a suspect.
• Hair/Fiber recovery: Materials are collected via tape-lift and maintained with acetate sheets.
• Hair/Fiber analysis: analyzed using microscopes and spectroscopy to study fibers and their pigments.
• Glass analysis: various chemical tests can be used to match glass fragments to a source or to eliminate a possibility of connection.

Soil as Evidence

• Soil analysis: includes analysis of bacterial DNA, pollen, particle size, and color.
• Quarz grain analysis: exclusionary evidence techniques are used to discredit possible alibis.

Class and Individual Evidence

• Class characteristics: are not unique to any one object. This places an item of evidence into a broad category.
• Individual characteristics: are unique to particular objects, narrowing the evidence down to one individual.

Firearms

• Firearm examination: involves visually examining, weighing, and measuring firearms and their parts. Standard firearms are used as controls to analyze firearms in question.
• Firing capability and bullets: analyzed to ascertain firing capabilities and match potential bullet type.

Cartridge Cases, Gunshot Residue, and the Crime Scene

Determining/Examining bullet types recovered from crime scene can be compared to those obtained from the suspect's firearm or other potential sources.

• Characteristics of rifling grooves (number, type, and depth) on firearm barrels allow for firearm type classification and identification.
• Techniques for identifying and determining gunshot residue (GSR) are used for determining if someone has recently fired a gun.
• Crime scene examination: The purpose is to locate, identify, collect and preserve evidence.

Investigating Toolmarks

• Toolmarks: are any impression, cut, gouge ,or abrasion on a surface (three-dimensional).
• Tools used to cause harm are often harder than the surfaces they strike.
• Examples of types of tools are those used for cutting, prying, or striking.
• Toolmark analysis helps to identify tool use and potential force used.

Recovering/Recording Toolmarks

Recording evidence of toolmarks involves photography and the use of casting methods (moulds) of impressions to remove and/or analyze an area affected by a tool.

Footwear Impressions

Analysis of two-dimensional and three-dimensional footwear impressions helps to link individuals to areas of a crime scene through the location of footwear.

Tyre Marks

• Tyre marks left by vehicles can help to pinpoint the possible vehicle that committed an act or the origin of the culprit vehicle. Tyre marks can indicate direction and type of vehicle.

Post-Mortem Interval

• Time of death: the time elapsed from the moment of death until the discovery of the corpse.
• Three estimations of time of death are determined for the legal and scientific perspective: physiological legal estimated
• Methods to determine post-mortem interval include body temperature, rigor mortis, and lividity and other methods.

Body Temperature (Algor Mortis)

• Body temperature: (algor mortis) core temperature is estimated to assist in determining time of death.
• The factors that effect this are environmental temperature and the body's own temperature initially.
• Limitations include, body mass, movement of air, humidity, clothing, and water immersion.

Rigidity (Rigor Mortis)

• Rigor mortis begins in the face and neck muscles, proceeding down to other parts of the body.
• Rigor mortis is fully established within 8-12 hours, and it remains for a further 2-3 days, then disappears.
• Factors which effect this include, violent exercise before death and the rate of heat and cold effect on the body.

Lividity (Livor Mortis)

• Lividity develops within 3-4 hours of death, and it becomes fixed and unmovable after approximately 12 hours.

Vitreous Humor of the Eye

• Potassium levels in the vitreous humor of the eye (in retinal blood cells) increase after death.

Other Biochemcial Markers

• Several biochemical markers exist which are assessed which are assessed to estimate time of death.

Supravital Reactions, Stomach Contents, Decomposition, Putrefaction

• Assessing the stomach contents for the presence or absence of contents can give an indication of the time of death and potentially give a level of indication surrounding if any physical or emotional distress was suffered by the victim(s).
• Decomposition is the breakdown and decomposition of the body after death, and there are 5 stages of this including putrefaction.

Entomology

• Entomologists are trained in the identification and knowledge of insect stages and life cycles, with special consideration for climate and temperature parameters surrounding a crime location.

Forensic Pathology

• Forensic pathology: the investigation of deaths where there are medico-legal implications.
• This discipline encompasses cases like suspected homicides, in custody deaths, and other complex medico-legal cases.
• It assists in establishing cause(s) of death through examinations, analyses, and investigations (often using external examination of the body, organs, or blood).

Autopsy

• Autopsy (post-mortem): An examination of a dead body performed to determine the cause of death.
• Process: begins with complete external examination, including vital signs and marks, follows by internal examination involving incisions and organ/tissue analyses.
• Purpose: to determine the cause, manner and medical history relevant to the death.

Identification of Remains

• Forensic pathologists: may need to identify remains using identifying evidence like DNA, fingerprints, dental records, tattoos, or skeletal information to match the deceased to their identity.

Identifying the Cause of Death

• Wounds: damage to tissues caused by mechanical force. Examples include punching, kicking, bite marks, stab wounds, strangulation, shooting, drowning, poisoning, and explosion.
• Cause of death can be complex, but identification of wounds assists in building a cause of death narrative.

Nature of Wounds

• Forensic pathologists need to document the type, size, depth and location of injuries to help determine the source of injuries and potentially the motive surrounding the cause of death.

Gunshot Evidence and Death from Explosion

• Determining the type of weapon and the trajectory of the bullet (entrance and exit points).
• Examining the explosion site gives an indication of the type and timing of any explosions.

Drowning

• Drowning is assessed via physical examination to ascertain that the cause of death is definitively drowning.

Presumptive Testing

• Preliminary tests like color tests can rapidly identify potential substances and components but may not be conclusive enough on their own to definitively ascertain the presence or absence of a compound or drug.

Confirmatory Testing

• More complex and conclusive tests are used when identifying and qualifying materials detected via presumptive tests.

Forensic Services Providers

• Private and public organizations or entities provide forensic services. They can be utilized by the police, or the defense or prosecution teams to provide scientific evidence to assist in determining cause of effects in court.

The Court and Evidence

• Providing evidence in court from all analyses requires accurate information and data.
• This may need to be reviewed and confirmed for accuracy.