the laboratory be accredited and that specific procedures be in place and followed. In accredited laboratories, forensic DNA personnel must take proficiency tests and must meet specific educational and training requirements. (See Chapter 8 for further discussion.) Laboratory analyses are conducted by scientists with degrees ranging from a bachelor’s degree in science to a doctoral degree. Each forensic DNA laboratory has a technical leader, who normally must meet additional experience and educational requirements.

Although DNA laboratories are expected to conduct their examinations under stringent quality controlled environments, errors do occasionally occur. They usually involve situations in which interpretational ambiguities occur or in which samples were inappropriately processed and/or contaminated in the laboratory. Errors also can occur when there are limited amounts of DNA, which limits the amount of test information and increases the chance of misinterpretation. Casework reviews of mtDNA analysis suggest a wide range in the quality of testing results that include contamination, inexperience in interpreting mixtures, and differences in how a test is conducted.¹⁰

FBI quality guidelines require that reports from forensic DNA analysis must contain, at a minimum, a description of the evidence examined, a listing of the loci analyzed, a description of the methodology, results and/or conclusions, and an interpretative statement (either quantitative or qualitative) concerning the inference to be drawn from the analysis.¹¹