Strengthening Forensic Science in the United States a Path Forward.
Private investigators may find this link useful they can read almost the entire book online.
Here is an excerpt from page 36:
"Not all forensic services are performed in traditional crime laboratories by trained forensic scientists. Some forensic tests might be conducted by a sworn law enforcement officer with no scientific training or credentials, other than experience. In smaller jurisdictions, members of the local police or sheriff’s department might conduct the analyses of evidence, such as latent print examinations and footwear comparisons. In the United States, if evidence is sent to a crime laboratory, that facility might be publicly or privately operated, although private laboratories typically do not visit crime scenes to collect evidence or serve as the first recipient of physical evidence. Public crime laboratories are organized at the city, county, state, or federal level. A law enforcement agency that does not operate its own crime laboratory typically has access to a higher-level laboratory (e.g., at the state or county level) or a private laboratory for analysis of evidence."
Here is a little trick I learned reading books online.
When reading this book online eventually you will be prompted to purchase the book. To continue reading the book click the "back arrow" button to return to the page you just finished, then continue reading normallly.
Link: http://books.nap.edu/openbook.php?record_id=12589&page=35