Molecular Biology, Forensic Odontology, and Physical Anthropology
This domain covers identification and the biology underlying it. Molecular concepts: DNA profiling (STR loci), PCR amplification, degradation and inhibition, mixture interpretation, likelihood ratios, and the statistical weight of a match; mitochondrial DNA for maternal lineage and degraded samples; Y-STR for male lineage; and quality control in the laboratory. Traps include overstating a random match probability, ignoring contamination and low-template DNA, and confusing inclusion with identification.
Odontology: dental identification through charting, radiographs, and unique restorations; bite mark analysis is now viewed with caution and should not be the sole basis for identification or conviction. Age estimation from tooth eruption and wear. Anthropology: sex from pelvis and skull, age from pubic symphysis, auricular surface, and cranial sutures, stature from long bones, ancestry from craniometrics (with caution), and taphonomy (postmortem change, animal scavenging, burning). Traps: assigning sex from a single trait, overreliance on ancestry estimation, and confusing perimortem with postmortem fracture (perimortem bone is green and breaks with hinging; postmortem is dry and brittle).
Worked example
A charred body has no fingerprints. Rule of thumb: use dental charting and radiographs first for identification, then DNA from a protected site (tooth pulp, bone) if needed. Bite mark evidence alone should not establish identity.
Always state the limitations and the statistical weight of identification methods.