How are unknown or questioned samples and known samples alike or different?

Question

What will be an ideal response?

Answer 1

Much of the work of forensic science is in making comparisons of various types of samples. There are specialized terms to refer to these samples, and it is important to know what they mean so that you can communicate with the laboratory and understand lab reports.
At the most general level, comparison samples may be from unknown/questioned or known sources, each of which has three subcategories.
Unknown samples:

1. Recovered crime scene samples whose source is in question,
2. questioned evidence that may have been transferred to an offender during the commission of a crime and taken away by him or her, and
3. evidence from an unknown/questioned source that can be used to link multiple offenses together that were committed by the same person using the same tool, or weapon.

Known samples:

1. Standard/reference samples are material from a known/verifiable source,
2. control/blank samples are from a known source that was uncontaminated by the crime and are used to make sure that the evidence on which the evidence was deposited does not interfere with laboratory testing, and
3. elimination samples, which are taken from a source known to have had lawful access to the crime scene to be used to compare with unknown samples of the same type from that scene.