1. What are the four types of evidence in a criminal investigation? The four types of evidence is physical evidence, documentary evidence, demonstrative evidence and testimony.
2. What are individual characteristics? Give an example of an individual characteristic?
Individual characteristics are properties associated with a common source to a high degree of certainty. An example of individual characteristics that forensic scientists may look for are the ridge characteristics of two fingerprint samples.
3. What is the difference between individual characteristics and class characteristics?
Class characteristics are those that can only be associated with groups not just a single source
4. What are physical and chemical properties? Give an example of each. Physical properties are those that describe a substance or object without referring to any other substance. For example the physical properties of glass might be its weight, size, color, and volume. The physical properties are those that an object or trace evidence has with just its physical existence, without altering it in any way with chemicals.Chemical properties are those that describe what happens when a substance reacts with another substance. For example, when the drug heroin comes into contact with the Marquis reagent chemical it turns purple. This behavior describes the chemical property of heroin and helps forensic scientists identify its presence.
5. What do forensic scientists do to collect and preserve soil samples? Soil samples are typically collected from the crime scene within a 100-yard radius at various spots. Forensic scientists take great care in collecting and preserving soil samples, if soil is found on the bottom of a shoe for example the soil is left on the shoe and the entire shoe is taken to the crime lab. The object must also be stored in such a way that any pieces of dirt that may fall off the object are retained.
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? If the actions are not taken correctly then if you might mess up or accidental loose some evidence you have some more, they label to help with the specifics. If they are less careful about this then it might not be any use to them and just be a waste of their time.
2.Which type of evidence do you think is most useful in an investigation? Why?
I believe that the most useful evidence is physical evidence because it helps give more detail than any other type of evidence.
3. Why do you think that forensic scientists continue to look for class characteristics given their limitations?
Forensic scientist might continue to look for class characteristics because they would like more evidence to convict or help with other law binding reasons.
4.What do you think would be some of the challenges in collecting and preserving impressions? Why?
I believe that some challenges might be having to be very gentle and cautious about what you do and how you treat the evidence.
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? I believe I would expect individual characteristics because that would help me make some serious and maybe even final decisions.