One section explains the science of nuclear DNA (deoxyribonucleic acid), followed by a description of DNA and STR (short tandem repeat) technology. A section then addresses mitochondrial DNA, which is found in the mitochondria of a cell, outside the nucleus in the cytoplasm. It is found in bone, muscle, hair, teeth, skin, blood, and body fluids; like nuclear DNA, it can be located, extracted, and copied. A section on the math of forensic identification focuses on the calculation of statistical probabilities when describing the rarity or frequency of finding the defendant's DNA profile (which matches the DNA profile found at the crime scene) among human populations. The next section discusses how DNA evidence can be used not only to establish the identity of the offender but also to establish other elements of how, when, and where the crime occurred. The discussion then turns to the use of DNA evidence in trials, as it focuses on admissibility, discovery, the case-in-chief, defense experts, and closing argument. 4 figures, 9 resources, and a glossary of DNA terms