Forensic Science Worksheet for 17-Year-Olds | High School Science Case Activities

Instructions

Read each section carefully and answer the questions to the best of your ability. Use your knowledge of forensic science principles to solve the problems presented. This worksheet covers various disciplines within forensic science, from evidence collection to analysis.

Part 1: Terminology Match

Match the forensic term in the left column with its correct description in the right column. Write the corresponding letter in the blank space.

Part 2: Short Answer & Critical Thinking

Answer the following questions in the space provided. Your answers should be clear and concise.

1. Explain the primary difference between class evidence and individual evidence. Provide one example of each that might be found at a crime scene.

   Difference:

   
   

   Class Evidence Example:

   
   

   Individual Evidence Example:

   
   
2. A latent fingerprint is discovered on a ransom note (paper). What chemical method would be most appropriate for visualizing this print, and why is it preferred for porous surfaces?

   Method:

   
   

   Reasoning:

   
   
3. Investigators find a skeletonized body in a remote, wooded area. What two key pieces of information could a forensic anthropologist likely determine from the remains, and which specific bones would they examine to do so?

   Information 1 & Bone(s):

   
   

   Information 2 & Bone(s):

   
   

Part 3: Crime Scene Scenario Analysis

Scenario: You are called to a potential homicide scene. Inside a luxury apartment, a male victim is found deceased on the floor. There are no obvious signs of forced entry. On a glass coffee table, there is a wine glass with lipstick residue on the rim, a half-empty bottle of wine, and a smartphone. Near the victim's body, a single spent 9mm cartridge casing is found. A partial, bloody shoeprint is visible on the light-colored tile floor leading away from the body.

1. List five distinct pieces of physical evidence from this scene that should be collected and analyzed.
2. For three of the pieces of evidence you listed, identify the specialized forensic unit that would handle its analysis and state what crucial question the analysis could answer.

Evidence List:

• 1.
• 2.
• 3.
• 4.
• 5.

Evidence Analysis:

• Evidence Item 1:

  Unit:

  Question Answered:



• Evidence Item 2:

  Unit:

  Question Answered:



• Evidence Item 3:

  Unit:

  Question Answered:

Part 4: Quantitative Analysis - Bloodstain Pattern

Bloodstain Pattern Analysis (BPA) can help reconstruct events at a crime scene. The angle at which a blood drop strikes a surface can be calculated using trigonometry. A more elongated stain indicates a more acute angle of impact.

The formula is: Angle of Impact = arcsin (Width / Length)

Problem: An analyst measures a bloodstain at a scene. Its width is 6.2 mm and its length is 12.4 mm.

1. Calculate the angle of impact. Show your calculation. (A calculator with an arcsin or sin^-1 function is needed).


2. If another stain was found that was almost perfectly circular, what would you conclude about its angle of impact?

Calculation:

Conclusion for circular stain:

Answer Key

Part 1: Terminology Match

1. D Locard's Exchange Principle
2. F PCR (Polymerase Chain Reaction)
3. A CODIS
4. B Ballistics
5. C Toxicology
6. E Entomology
7. G STR (Short Tandem Repeat)

Part 2: Short Answer & Critical Thinking

1. Difference: Class evidence connects an item to a group (e.g., a brand of shoe), while individual evidence links a sample to a single, unique source (e.g., a specific person's fingerprint).
   Class Evidence Example: A strand of synthetic fiber from a common type of carpet; a particular brand of soil.
   Individual Evidence Example: DNA from a bloodstain; a fingerprint; striations on a bullet that match a specific firearm.
2. Method: Ninhydrin development.
   Reasoning: Ninhydrin reacts with the amino acids present in fingerprint sweat residue. Since paper is porous, the sweat absorbs into the paper fibers. Ninhydrin solution can be sprayed or brushed onto the paper, where it will soak in and react with these absorbed amino acids, producing a purple-colored print (Ruhemann's purple). Methods like powder dusting are ineffective as they only adhere to residue on the surface of non-porous items.
3. (Acceptable answers may vary slightly, but should include similar points)
   Information 1 & Bone(s): Sex. A forensic anthropologist would examine the pelvis (specifically the sub-pubic angle and sciatic notch) and the skull (examining features like the brow ridge and mastoid process). The female pelvis is generally wider than the male's.
   Information 2 & Bone(s): Age at death. This can be estimated by examining the fusion of epiphyses (growth plates) in long bones like the femur or humerus for younger individuals, or by observing the degree of wear on pubic symphysis (where the pelvic bones meet) for adults. Dental eruption patterns are also used for younger individuals.

Part 3: Crime Scene Scenario Analysis

Evidence List (any five of the following):

• 1. Wine glass (for fingerprints, DNA from saliva, lipstick trace)
• 2. Wine bottle (for fingerprints)
• 3. Smartphone (for digital evidence)
• 4. Spent 9mm cartridge casing (for ballistics/firearm identification)
• 5. Bloody shoeprint (for pattern, blood for DNA)
• 6. Victim's clothing (for trace evidence)
• 7. Victim's fingernail scrapings (for potential suspect DNA)

Evidence Analysis (examples):

• Evidence Item 1: Wine glass

  Unit: Latent Prints Unit; DNA Lab

  Question Answered: Can we identify who drank from this glass? (Prints/DNA) Does the lipstick residue contain trace DNA or can it be matched to a suspect's lipstick?

• Evidence Item 2: Spent 9mm cartridge casing

  Unit: Ballistics/Firearms Unit

  Question Answered: Can the unique markings (from the firing pin, extractor, etc.) on the casing be matched to a specific firearm, potentially one owned by a suspect or found at another scene?

• Evidence Item 3: Bloody shoeprint

  Unit: Trace Evidence/Impressions Unit; DNA Lab

  Question Answered: What is the brand, model, and size of the shoe that made the print? (Class evidence) Is the blood from the victim? (Individual evidence via DNA)

Part 4: Quantitative Analysis - Bloodstain Pattern

1. Calculation:

   Angle = arcsin (Width / Length)

   Angle = arcsin (6.2 mm / 12.4 mm)

   Angle = arcsin (0.5)

   Angle = 30°

2. Conclusion for circular stain: A nearly perfectly circular stain indicates that the blood drop struck the surface at a perpendicular angle, approximately 90 degrees. As the angle decreases, the stain becomes more elliptical/elongated.