Forensic Science Study Notes

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Questions and Answers

A detective discovers a hair at a crime scene. Microscopic analysis reveals a medulla pattern characteristic of animal hair. According to forensic principles, what can the detective infer from this?

The hair may have originated from an animal present at the scene, potentially linking a suspect or providing information about the environment. (correct)
The hair is irrelevant to the investigation since it is not human.
The hair must have been transferred through Locard's Exchange Principle, indicating direct contact between the suspect and the victim.
The hair definitively belongs to the victim as animal hair is commonly found on clothing.

At a suspected crime scene, investigators identify a reddish-brown stain. Initial testing with Kastle-Meyer reagent yields a positive result. What is the MOST appropriate next step?

Conduct confirmatory tests like ABO typing or DNA profiling to confirm the stain is blood and determine its source. (correct)
Conclude that the stain is definitively blood and focus on blood spatter analysis.
Disregard the stain as the Kastle-Meyer test is conclusive on its own.
Document the stain as confirmed blood and proceed to DNA profiling.

An investigator is tasked with documenting the handling of a blood-stained knife found at a crime scene. Which protocol is MOST critical to maintain the integrity of the evidence?

Cleaning the knife to remove excess blood before packaging.
Immediately sending the knife to the lab for DNA analysis.
Photographing the knife at the crime scene before collecting it.
Establishing and meticulously documenting the chain of custody from the moment of discovery through analysis. (correct)

During a death investigation at a residence, the forensic entomologist observes blowfly larvae in the victim's remains. The ambient temperature has been relatively constant. How would this insect activity inform the estimation of the time of death?

<p>The entomologist can estimate the post-mortem interval (PMI) based on the blowfly lifecycle stages, considering factors like temperature and species. (C)</p> Signup and view all the answers

During a trial, a forensic ballistics expert is called to testify about their analysis of a bullet found at the crime scene. What factor would MOST significantly influence the admissibility of the expert's testimony and findings?

<p>Whether the expert's methods are generally accepted in the scientific community and have been properly applied in the case. (A)</p> Signup and view all the answers

Flashcards

Types of Evidence

Evidence found at a crime scene; can be physical (fingerprints, weapons), biological (blood, DNA), or trace (hair, fibers).

Chain of Custody

Documentation of evidence handling; vital to maintain integrity and admissibility in court.

Locard’s Exchange Principle

Every contact leaves a trace; cross-transfer of evidence occurs when two objects come into contact.

Manner of Death

Natural, Accidental, Homicide, Suicide, Undetermined; categorization of how a person died.

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Miranda Rights

Rights read to a suspect in custody, including the right to remain silent and the right to an attorney.

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Study Notes

Study notes on forensic science

Crime Scene Basics

Physical evidence includes items like fingerprints and weapons.
Biological evidence includes items like blood and DNA.
Trace evidence includes items like hair and fibers.
Chain of custody refers to documenting how evidence is handled.
Crime scene search patterns include grid, spiral, strip/line, and quadrant methods.
Locard’s Exchange Principle states that every contact leaves a trace.

Forensic Disciplines & Techniques

Fingerprint patterns are loops, whorls, and arches.
Fingerprint development techniques include dusting, iodine fuming, and ninhydrin application.
DNA analysis uses Short Tandem Repeats (STR).
Polymerase Chain Reaction (PCR) is used in DNA analysis.
Ballistics examines gunshot residue (GSR), rifling marks, and bullet trajectory.
Toxicology involves detecting poisons, drugs, and alcohol levels.

Death Investigation

Manner of death can be natural, accidental, homicide, suicide, or undetermined.
Stages of decomposition are rigor mortis, livor mortis, and algor mortis.
Forensic entomology uses insect activity to estimate time of death.

Blood & Bodily Fluids

Blood spatter analysis examines high vs. low velocity impacts and angles of impact.
The Kastle-Meyer test is a presumptive test for blood.
Luminol is used for blood detection.
Confirmatory tests include ABO typing and DNA profiling.

Impression & Trace Evidence

Shoe and tire prints are compared to known samples.
Tool mark analysis examines striation patterns and fracture matching.
Hair analysis involves medulla patterns to differentiate between human and animal hair.
Fiber analysis distinguishes between natural and synthetic fibers.