1. What are the four types of evidence in a criminal investigation?
1. Physical Evidence
2. Demonstrative Evidence
3. Documentary Evidence
2. What are individual characteristics? Give an example of an individual characteristic? -Individual Characteristics is evidence that have special characteristics that make it possible to trace the evidence back to a specific person, place or item. Some examples are fingerprints, body fluids, tread from shoes, etc. 3. What is the difference between individual characteristics and class characteristics? -The difference between these two are that individual characteristics can be traced to a specific person and be almost exact while Class Characteristics are able to just be associated to a group.
4. What are physical and chemical properties? Give an example of each.
-Physical Properties describe a substance or object. For example it could be the size, weight or color of a fragment of glass. -Chemical Properties describe what happen when a chemical reacts with another chemical. For example Heroin with Marquis Reagent turns purple and shows it presence of the drug.
5. What do forensic scientists do to collect and preserve soil samples? To collect the soil they impressions will be photographed with a ruler next to it to show the dimensions. To preserve the soil samples a whole shoe may be taken to the lab to test.
Critical Thinking Questions
1. Why do you think forensic scientists are so careful that the tests they do are sensitive, reproducible, and specific? What might happen if they were less careful about this? -The tests are so sensitive because if something is not accurate it could change the outcome of a case.
They must make sure that all test results are accurate a reproduce the same results multiple times for it to be reliable. 2. Which type of evidence do you think is most useful in an investigation? Why? -I think physical evidence is more important because it can be tested against suspects and establish what happened during the crime. 3. Why do you think that forensic scientists continue to look for class characteristics given their limitations? I think they continue to look for class characteristics because even if they are hard to come by when you find them the can give great details about the crime.
4. What do you think would be some of the challenges in collecting and preserving impressions? Why? Making casts of an impression may be difficult because if it is in mud it could distort the tracks. 5. If you were on a jury, do you think you would expect individual characteristics in the evidence? Why or why not? What effects might it have if individuals expect to have individuals characteristics presented? -No, because most of the time criminals are very careful to make sure not to leave evidence of being there. If you expect there to be individual evidence you may be completely mislead during the whole case.