Forensic Science Worksheet for 17-Year-Olds — High School Science

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Instructions

Read each section carefully and answer the questions to the best of your ability. Use your knowledge of forensic science principles to analyze the scenarios provided. This worksheet will test your understanding of key terminology, evidence analysis, and investigative procedures.

Part 1: Vocabulary Matching

Match the forensic term in Column A with its correct definition in Column B. Write the letter of the correct definition in the blank space provided.

Column A: Term
  1. ___ Locard's Exchange Principle
  2. ___ Chain of Custody
  3. ___ Algor Mortis
  4. ___ Rigor Mortis
  5. ___ Livor Mortis
  6. ___ Chromatography
  7. ___ AFIS
  8. ___ CODIS
  9. ___ Ballistics
  10. ___ Toxicology
 Column B: Definition

A. A national DNA database of convicted offenders, unsolved crime scene evidence, and missing persons.

B. The study of firearms, including the firing of a weapon and the flight of a bullet.

C. The stiffening of the body's muscles after death.

D. The principle stating that whenever two objects come into contact, there is a transfer of material.

E. The pooling of blood in the lower parts of the body after death, causing a purplish discoloration.

F. A national automated system for searching and matching fingerprints from a crime scene.

G. The study of poisons, toxins, and drugs and their effects on the human body.

H. A detailed, chronological log documenting the seizure, custody, control, transfer, analysis, and disposition of evidence.

I. A laboratory technique used to separate the components of a mixture.

J. The change in body temperature after death, typically a steady cooling until it matches the ambient temperature.

Part 2: Critical Thinking & Short Answer

Answer the following questions in the space provided. Your answers should be clear, concise, and demonstrate your understanding of forensic concepts.

  1. Explain the importance of maintaining a strict Chain of Custody for a piece of evidence. What is the most significant legal consequence if the chain is broken or improperly documented?

  2. A body is discovered in an apartment where the thermostat is set to 20°C (68°F). The body exhibits full rigor mortis. Lividity is fixed on the deceased's back. What can you infer about the approximate time since death and the position of the body? Explain your reasoning.

Part 3: Case Study Analysis

Read the following scenario and answer the questions that follow.

Scenario: At 2:00 AM, police respond to a silent alarm at a small, independent art gallery. The front glass door has been shattered. Inside, a valuable painting has been cut from its frame. Investigators note the following at the scene:

  • A single, clear shoeprint in a puddle of water just inside the door.
  • A small swatch of dark red cotton fiber caught on the broken edge of the door's frame.
  • A crowbar lying on the floor near the empty painting frame.
  • A single drop of what appears to be blood on the white wall next to the empty frame.
  • A handwritten ransom note left on the gallery's reception desk.

  1. Identify four distinct pieces of physical evidence from the scenario.

  2. For each piece of evidence you identified, classify it as either class evidence or individual evidence. Briefly justify your classification for two of them.

  3. As the lead investigator, what forensic analysis would you prioritize for the crowbar and the handwritten note? Explain why.

Part 4: Fingerprint Identification

Based on the following descriptions of ridge patterns, identify the type of fingerprint: Loop, Whorl, or Arch.

  1. Ridges enter from one side of the print, rise in the center to form a wave-like pattern, and exit on the opposite side. There are no deltas.
    Answer: ____________________
  2. Ridges form a circular or spiral pattern, resembling a whirlpool. This pattern has at least two deltas.
    Answer: ____________________
  3. Ridges enter from one side of the print, curve around, and exit on the same side. This is the most common fingerprint pattern and has one delta.
    Answer: ____________________



Answer Key

Part 1: Vocabulary Matching

  1. D - Locard's Exchange Principle
  2. H - Chain of Custody
  3. J - Algor Mortis
  4. C - Rigor Mortis
  5. E - Livor Mortis
  6. I - Chromatography
  7. F - AFIS
  8. A - CODIS
  9. B - Ballistics
  10. G - Toxicology

Part 2: Critical Thinking & Short Answer

  1. Answer: A strict Chain of Custody is crucial because it provides a legal record of everyone who has been in possession of a piece of evidence, ensuring its integrity and authenticity. It proves that the evidence has not been tampered with, contaminated, or substituted. The most significant legal consequence of a broken chain is that the evidence can be ruled inadmissible in court, meaning it cannot be used to support the case, which could lead to an acquittal of a guilty party.

  2. Answer: Full rigor mortis typically begins around 2 hours, peaks around 12 hours, and disappears after 36-48 hours. The presence of full rigor suggests the time since death is likely in the range of 8-24 hours. Fixed lividity (livor mortis) on the back indicates that the deceased was lying on their back for a significant period after death (at least 6-8 hours) and has not been moved since the lividity became fixed. The body's position has remained supine (on its back) post-mortem.

Part 3: Case Study Analysis

  1. Answer: Four pieces of evidence include: (1) Shoeprint, (2) Red cotton fiber, (3) Crowbar, (4) Blood drop, (5) Ransom note.

  2. Answer:

    • Shoeprint: Can be class evidence (brand, size) but may become individual evidence if it has unique wear patterns, cuts, or embedded debris.
    • Red cotton fiber: Class evidence, as it can be traced to a type of garment (e.g., a red cotton sweatshirt) but not to a single specific garment without a physical match.
    • Crowbar: Class evidence (brand, type) but can yield individual evidence like fingerprints, DNA, or unique markings (tool marks).
    • Blood drop: Individual evidence, because DNA analysis can trace it back to a single person with extremely high probability.
    • Ransom note: Individual evidence, as handwriting analysis (graphology) and analysis of fingerprints on the paper can link it to a specific individual.
    (Justification requires explaining why it points to a group vs. a single source).

  3. Answer:

    • Crowbar: The priority would be to check for latent fingerprints and trace DNA (touch DNA from skin cells). If the crowbar was used to pry something, its unique marks (tool marks) could also be compared to marks left at the scene.
    • Handwritten note: The priority would be forensic document examination (graphology) to analyze the handwriting style, ink, and paper. It should also be processed for latent fingerprints.

Part 4: Fingerprint Identification

  1. Answer: Arch
  2. Answer: Whorl
  3. Answer: Loop
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