Fitzpatrick applied Y-STR analysis to the Chandler profile. Y-STR — short tandem repeat analysis of the Y chromosome — examines specific locations on the Y chromosome where sequences of DNA letters repeat in varying numbers. These repeat patterns are compared against public databases maintained by genealogical research organizations, where individuals interested in tracing their paternal ancestry have submitted their own Y-STR profiles.
Because the Y chromosome is passed from father to son across generations with very little change, a Y-STR profile can often establish a patrilineal surname even when conventional genealogical records are unavailable. The mutation rate of the relevant sequences is low enough that the Y-STR profile of a man and his patrilineal male relatives — grandfather, uncles, brothers, cousins through the male line — will be very similar or identical, and that similarity clusters around surnames.
The comparison of the Chandler Y-STR profile against available databases returned a result pointing to the surname Nicholas or Nichols — or a closely related spelling variant. This was a significant finding, because it meant the investigation was not searching through the entire universe of possible surnames. It was looking at a specific surname cluster.
But a surname is not an identity. “Nichols” is a relatively common name in the United States, with hundreds of thousands of bearers. Knowing that the deceased’s paternal ancestry traced to a Nichols line narrowed the field enormously but did not resolve it. Further work was needed.
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## The DNA Doe Project: Adapting Techniques to Degraded Material
The DNA Doe Project entered the Chandler case in 2018, building on the surname lead that Fitzpatrick’s Y-STR analysis had established. The DNA Doe Project was a nonprofit organization co-founded by Dr. Fitzpatrick and Dr. Margaret Press that applied forensic genealogy to cases of unidentified deceased persons — “John Does” and “Jane Does” — using the same basic approach that consumer genetic testing companies use, but directed toward identification rather than ancestry exploration.