Traditional forensic identification relies primarily on fingerprints, dental records, and DNA matches in law enforcement databases. Fingerprints require intact skin — not available in the Chandler case due to decomposition. Dental records require prior dental records to compare against — which would require knowing who the person was in order to obtain them, a circular problem for an unidentified person. CODIS searches require that the unknown person’s DNA be in the system through a prior criminal conviction or voluntary submission — which Nichols had never provided.
The genealogical DNA approach bypassed all of these limitations by working not from the unknown individual’s own record but from the records of his relatives. As long as some biological relative — even a distant cousin — had voluntarily submitted a DNA profile to a consumer testing service or genealogy database, a connection could potentially be made.
The specific innovation in the Chandler case was adapting this approach to work with severely degraded DNA. The 7% of the genome that remained usable after fifteen years of paraffin preservation was not enough for the standard implementation of the technique, which relied on a full or near-full SNP profile. The DNA Doe Project’s solution — multiple sequencing rounds, careful combination of results, careful analysis of the resulting partial profile against database matches — extended the technique into territory that had previously seemed inaccessible.
This extension has implications for future cases. Many unidentified persons whose remains have been preserved for pathological purposes — in hospitals, medical examiners’ offices, and other institutions — were preserved in conditions similar to those that affected the Chandler sample. Paraffin-embedded tissue is the standard preservation method for histological samples. If forensic genealogy can work with DNA from such samples even at 7% genomic coverage, the universe of potentially identifiable cold cases is considerably larger than it appeared before the Chandler identification.