Make a COPY of the worksheet to your own Google Drive: https://docs.google.com/document/d/1noMzXi9vXbXVZX3woZrFSTaHO52ZJ5UKL0375mSvSVY/edit?usp=sharing

The Language of Science

Start by completing the “Language of Science” activity linked below. After completing the vocabulary activity, return to this page to do the Forensics lab.

The Language of Science: Mastering Scientific Vocabulary

CSI Sonoma State: Forensics Lab

Meet Bella

Examine Your Own Fingerprints

To complete this activity, you will “fingerprint” yourself on scratch paper using common household items. If you don’t have an actual inkpad at home, you can make your own in one of the following ways:

• “Color” your finger with a water-based marker, and press your finger to the paper before the ink dries.
• Make an “ink pad” with a graphite (#2, etc) pencil. Use the pencil to color in a square on a piece of paper. Cover the paper thoroughly, then press your finger into the square. You should pick up some of the graphite on your finger ridges. Press your finger into a black piece of paper to see the fingerprint. Alternately, you could press your “inked” finger onto a piece of clear cellophane tape to capture the pattern in the ridges.
• Mix equal portions of water and liquid tempera craft paint. Stir thoroughly to incorporate the two. Place a dry sponge into the mixture to soak up the colored water, then squeeze it to drain excess.

1. What is the general friction ridge pattern of each finger? (Report these percentages to your lab instructor, for an activity later in the lab).
2. Can you identify any minutiae? Circle them on the prints above, and list them below:

Biotechnology

DNA fingerprinting is a laboratory technique used to determine the probable identity of a person based on the nucleotide sequences of certain regions of human DNA that are unique to individuals. DNA fingerprinting is used in a variety of situations, such as criminal investigations, other forensic purposes and paternity testing. In these situations, one aims to “match” two DNA fingerprints with one another, such as a DNA sample from a known person and one from an unknown person.

• Which man (Dad 1 or Dad 2) appears to be the father, based on the results of gel electrophoresis Paternity Test below?

Mass Spectrometry is an analytical tool used to identify unknown compounds via molecular weight determination. In forensic investigations, it can be used to identify the compounds found in:

• Toxins in tissues or body fluids
• Dyes in carpet fibers
• Glass fragments
• Paint samples
• Accelerants or explosive residues

Chemicals are identified by looking at the peaks for a characteristic signature (the height of the peak).

Calculating Time of Death using the Stages of Death

Use the tables below to estimate the approximate time of death for the situations listed in your lab worksheet. Explain each of your answers:

1. A body was found with no evidence of rigor.
2. A body was found exhibiting rigor throughout the entire body.
3. A body was discovered with rigor present in the legs, but no rigor in the upper torso.
4. A body was discovered in the woods. The man had been missing for two days. The average temperature the past 48 hours was 50 degrees Fahrenheit. When the body was discovered, it was at peak rigor.
5. The victim was found in a snowbank alongside a road. His body is rigid. How long has he been dead? Explain your answer.

Use the information about Algor Mortis below to answer the following questions. Show your work.

6. Approximately how long has the victim been dead if his body temperature was 33.1°C (91.6°F)?
7. A body found outside in the winter has a temperature of 33.1°C. Has the body been dead a longer or shorter time than in #6? Explain your answer.
8. What is the approximate time of death if the body temperature was 15.6°C (60.8°F)?
9. What is the approximate time of death if the body temperature was 24°C (75°F)?

Describe the impact on time of death for each of the variables listed below. If you based your time of death estimates strictly on temperature loss to be 10 hours earlier, would you reduce your 10-hour estimate or increase your 10-hour estimate if the body had been:

10. Naked
11. Exposed to windy conditions
12. Suffering from an illness prior to death
13. Submerged in a lake

Follow-up Question:

14. What is the significance of determining the time of death? Why is it so important to crime-scene investigators to take the temperature of the deceased body if the person is already known to be dead?

Determining Time of Death with Entomology

For the case studies below, examine the insects collected from each corpse, and use the chart provided to estimate the time of death.    

INVESTIGATION #1

Police Report: The body of a female deer was found behind a fence along a busy two-lane road on the edge of the city limits of Santa Rosa. Animal Control was called and reported no apparent wounds on the body. It was not hunting season.

Weather Report: Daytime temperatures have been fairly consistent for the past three weeks, ranging from 70 to 74º F.

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1. Approximately how long has this animal been dead?
2. Why are maggots of different ages found in the body?
3. Other than temperature, what abiotic (external to the corpse) conditions would you want to obtain from the weather station to help you to be more confident of your time of death estimation?

INVESTIGATION #2

Police Report: The body of a coyote was found in an empty dumpster in the alley of a Rohnert Park neighborhood. Hairs around the animal’s neck were worn away in a band pattern. The dumpster lid was closed, and the temperature inside was recorded as 55º F.

Weather Report: Daytime temperatures have been variable over the past three weeks, ranging from 50 to 65º F.

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1. Approximately how long has this animal been dead?
2. What effect, if any, do the outside temperatures have on your estimation of time of death?
3.What does the location and condition of the body suggest about the situation? Explain.

INVESTIGATION #3

Police Report: The body of a mountain lion was found in a dense stand of trees far from any urban area on Sonoma Mountain. Maggots were found concentrated in the head and region behind the shoulder.

Weather Report: Daytime temperatures had been average over the past three weeks, ranging from 70 to 73º F. Temperatures in the woods would be approximately 5 degrees cooler due to the lack of sun in the shady environment.

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1. Approximately how long has this animal been dead?
2. What effect, if any, does temperature have on your estimation of time of death?
3. Can you speculate about why the insects were concentrated in certain parts of the mountain lion’s body?  

Fingerprint Pattern Percentages

You will not be able to compare your fingerprint results to those of other students, but you can compare them to the national average, show below. How close are your percentages to the national average?

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