Forensic Science Lab Questions

7 July 2016

1. What physical evidence did you find at the victim’s home? A box of matches, a space heater, beer bottles, Natalie’s wallet, a V-shaped burn pattern, burned outlet, a protected surface on the ground, crazed glass, and a puddle-shaped burn pattern. 2. Describe the process that you used to take a sample of the puddle-shaped burn pattern on the floor. Why did you also take samples from the portion of the floor that was not burned? First, I took the chisel to loosen up some of the wood chips in the puddle-shaped area. Then I used I took tweezers to put loose wood chips into an air tight sealed can.

Samples needed to be taken from the portion of the floor that was not burned because you need a control to compare to how the wood was before the burned pattern. 3. What evidence did the space heater provide? What did the evidence indicate? There was a cloth on the heater, the heater was on when the fire was started (on high, and there was a faulty electrical cord (the electrical cord was heated over the melting temperature and the wires melted. ) There was no sharp demarcation. The evidence suggests that it could have caused the fire, but it was mostly on accident (most likely from human negligence.

Forensic Science Lab Questions Essay Example

) 4. What information did you gain from the pictures taken at the scene? The v-shaped pattern often occurs in the area where a fire originated, so it is possible that the space heater was the fire of origin (tests needs to be run to confirm). The crazed glass (by lab results) indicated that crazing is the result of rapid cooling of hot glass by the application of water. The protected surface shows there was an object on the floor protecting the area, and there is the shape of a body that was there during the fire.

The puddle-shaped burn often occurs in areas of intense burning, with or without the presence of ignitable liquids in the burn wood flooring (tests need to be run to confirm. ) The burn outlet indicates that the space heater could have been on during the fire (close examination needs to be done. ) 5. To whom did the fingerprints on the match box belong? What characteristics of the fingerprints helped you to determine they were a match? How long does the average IAFIS search take? The fingerprints from the match box belong to Donald Parker.

Characteristics that helped determine the match were the hook, bifurcation, island, another bifurcation, bridge, and ridge ending. It takes an average of two hours for the IAFIS search matches for fingerprints. 6. Why is there a charcoal strip inside the containers that you used to collect the floor pieces? Why are these pieces saved after the solution has been prepared for the GC? There is a charcoal strip inside the containers because it will absorb any vapors in the air space upon heating the flooring, vaporizing any chemicals that were in them. They are kept in case they have to run the analysis again. 7.

What elements were present in the gas chromatograph from your puddle sample? How did this differ from the control graph? Elements that were present in the gas chromatograph were perchlorethylene, gasoline, oak flooring, and 3-phenyltoluene. Gasoline cannot be found in the control sample. 8. While performing the autopsy to determine if the victim died in the fire, what signs of inhalation did you look for? Based on the graph, what percentage of carboxyhemoglobin in the blood is deadly? To see if there was soot in his lungs or trachea (which there was not. ) 60%-100% of carboxyhemoglobin in the blood is deadly. 9.

How does the spectrometer work? What does the absorption of light waves help you to determine? How did you use the calibration curve to determine the blood alcohol content? The spectrometer shoots a beam of light of a certain wavelength on the sample which contains two different molecules. ) A detector measures the intensity of the light that leaves the sample. Molecules in the sample absorb some light; the light that leaves the sample is less intense than the light that went into the sample. The absorption of light helps determine the different concentrations in the samples. You start by looking at the height and width of the ethanol peak.

You use the units on the x-axis and y-axis to determine the width/height of the peak. Since the peak is similar to an equilateral triangle, I can use the formula for the area of one to calculate the area of the peak. After the calculation is complete, I located the area of the peak on the y-axis, drew a straight line to the line, and went straight down to where it connected. 10. Explain how the evidence helped you to determine how Trevor died and whether the fire was accidental or arson. The test with the spectrometer confirms that the carboxyhemoglobin in his system was normal, which means he did not inhale smoke during the fire.

It mostly indicates that he did not die in the fire. Blood tests were run on Trevor and he had oxycodone in his system. When I visited the hospital to question Natalie, she had denied many things. On her file, it was shown that she had oxycodone in her system also. On the space heater, there was a piece of cloth on it (potentially causing the fire. ) Also, there was gasoline in the floor board, confirmed from the gas chromatography. Natalie had confirmed she poured gasoline on the space heater, and her shirt got caught on the space heater, and she set the place on fire.

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