Fingerprint Files
What are the three main fingerprint ridge patterns?
Loops, whorls, and arches.
What principle states that every contact leaves a trace?
Locard's Exchange Principle.
What is the first step of the scientific method?
Observation.
An eyewitness who actually saw a crime happen provides what type of evidence?
Direct evidence.
What is the term for evidence that is allowed to be presented in court?
Admissible evidence.
Which scientist established that fingerprints are unique and remain stable throughout a person's lifetime?
Sir Francis Galton.
Name TWO examples of trace evidence.
Any two: hair, fibers, soil, glass fragments, paint chips, or pollen.
What do scientists call a specific, testable explanation for an observation?
A hypothesis.
A shoe print found outside a broken window is what type of evidence?
Circumstantial evidence.
What standard helps judges determine whether scientific expert testimony is reliable enough to be presented in court?
The Daubert Standard.
What characteristic of fingerprints allows investigators to distinguish one person from another?
Their uniqueness.
A burglar leaves fibers from their jacket on a window frame and takes tiny glass fragments with them. What forensic concept does this demonstrate?
Two-way transfer of evidence (Locard's Exchange Principle).
What does objectivity mean in forensic science?
Evaluating evidence based on facts rather than feelings or personal beliefs.
Blood and skin cells belong to what category of evidence?
Biological evidence.
Name TWO factors judges may consider when applying the Daubert Standard.
Any two:
Whether the theory has been tested
Whether the error rate is known
Whether the work has been peer reviewed and published
Whether the method is widely accepted by scientists
How did Galton's fingerprint classification system help investigators?
It made large fingerprint collections easier to search and compare.
Which would likely transfer more trace evidence: briefly touching someone or being involved in a violent struggle? Why?
A violent struggle because more intense or prolonged contact generally transfers more material.
An investigator believes a suspect is guilty and only pays attention to evidence supporting that belief. What is this an example of?
Confirmation bias.
Why should biological evidence generally be stored in breathable paper rather than sealed in plastic?
Paper allows airflow, while plastic traps moisture that can damage biological evidence.
What is the role of an expert witness in a courtroom?
To explain scientific findings clearly, acknowledge limitations, and help the court understand the evidence.
A fingerprint is found on a broken window. What can investigators determine from the fingerprint, and what can they NOT determine from it alone?
It may help identify who touched the window, but it cannot prove that person committed the crime.
Investigators discover soil from a crime scene on a suspect's shoes. What could this evidence suggest, and what does it NOT prove?
It may link the suspect to the location, but it does not prove they committed the crime.
Name TWO methods forensic laboratories use to reduce bias.
Blind analysis and technical review.
Investigators have fingerprints, shoe prints, and DNA evidence that all point toward the same suspect. Why might these pieces of evidence be stronger together?
Multiple independent pieces of circumstantial evidence supporting the same conclusion can strengthen a case.
A forensic expert tells the jury, "This fingerprint proves with absolute certainty that the defendant committed the crime."
What is wrong with this statement?
The expert is overstating what the evidence can prove. A fingerprint may link someone to an object but cannot independently establish that they committed a crime.