Which forensic scientist is, in part, responsible for the very specific evidence collection guidelines that exist in an effort to avoid cross- contamination during the collection process?

The crime scene investigator is a forensic scientist that has a crucial responsibility of preserving evidence where they follow specific evidence collection guidelines in order to avoid cross-contamination during the collection process.

In addition, each type of evidence has a specific value in an investigation especially when the case goes to the court.  

cookies! make chocolate chips, but with orange chocolate!