Soils Quiz

Criminalist Jared Heath responds to the scene of an assault, on an unpaved lane in a rural area. Rain had fallen steadily the night before, making the area quite muddy. A suspect with very muddy shoes was apprehended nearby but claims to have picked up the mud either from his garden or from the unpaved parking lot of a local restaurant. Jared uses a spade to remove several samples of soil, each about 2 inches deep, from the immediate crime scene and places each in a separate plastic vial. He collects the muddy shoes and wraps the in plastic as well. At the laboratory, he unpacks the soil samples and examines them carefully, one at a time. He then analyzes the soil on the shoes to see whether it matches the soil from the crime scene. List 2 mistakes, if any, that Jared made. Jared made several mistakes. First, the samples he removed from the scene should have included only the top layer of soil. Second, he failed to collect soil samples from both alibi locations—the garden and the parking lot. Third, he should have packaged the shoes in paper, not plastic. Finally, he should have dried all of the soil samples under identical laboratory conditions before examining any of them.

2. What is the logical first step in soil analysis. a 2. What is the logical first step in soil analysis? a. Examination for presence of debris under low-power magnification b. Comparison of dried soil sample for color and texture c. Use of the density-gradient tube technique d. Examination of minerals and rocks under high-power magnification b

3. Which would be LEAST useful in identifying a mineral crystal. a 3. Which would be LEAST useful in identifying a mineral crystal? a. Size b. Color c. Geometric shape d. Refractive index a

4. True or False, Standard/reference soil samples should be collected at the site of the crime at various intervals within a designated radius of the crime scene. True

5. True or False, If soil is found adhering to an object, the investigator should remove the soil particles from the object and send them to the laboratory. False

6. A forensic scientist examines a soil sample using a microscope 6. A forensic scientist examines a soil sample using a microscope. She finds small, rounded grains made up of quartz crystals. There are also small bits of coral present. From this information, what can you conclude about the origin of the soil. The presence of coral would indicate that it came from a tropical region. The presence of quartz indicates it is from a land source. Because grains are rounded this would indicate the sand is old.

7. Sand from different locations contains different combinations of minerals. The most common mineral found in sand is: a. mica b. feldspar c. quartz d. an iron compound c.

8. You are sent to collect soil evidence from a house that has been burglarized. Briefly describe how you would go about collecting samples. Document all sample by taking photographs Sketch the scene Collect samples as soon as possible Collect surface samples and samples that appear different Collect ~4 Tbls from several locations Package items that have soil attached instead of removing Remove soil from vehicles and package separately Collect samples at all alibi locations