Familia DNA, CSI And A Cigar Left On The Street

This is the story of three living grandsons or “cousins” but only two were known to each other and to the family. One of these two committed a murder but it was his half-brother unknown to the family who was arrested, convicted and was serving time for murder. 

A man (Grandfather Y) and a woman (Grandmother X) had three sons in the 1940’s. These three sons were adults around 1970 but are no longer alive. The blue icons in the family tree are three women who were outside the family and had the grandsons of Grandfather Y and Grandmother X. Woman Gamma was unknown to all but Son 1. Son 1 had a son (Grandson B) with Woman Alpha. Grandson B was known to the family. Son 1’s brother (Son 3) had two sons but only one (Grandson C) is alive (Grandson D was killed in an auto accident). Grandson C was only aware that he had a cousin but had not seen him in quite some time and believed his cousin Grandson B lived New York City (in fact Grandson B left for NYC after committing the crime). Woman Beta who was still alive told also thought her nephew lived in NYC.

Son 1 had another son with another woman (Woman Gamma). His wife (Woman Alpha) was never aware of this other son. None of Son 1’s brothers, sister in-law or nephews were ever aware of his son, Grandson A. 

Thus, Grandson A and Grandson B are half-brothers but never knew about one another (their mothers also were unaware of each other’s existence). Grandson B committed a murder around 1990 in a high-profile case. He fled the area to New York City, was unknown to local law enforcement where the crime occurred and was thus never considered as a suspect. Grandson A had a few non-violent crimes to his record and was arrested and confessed to a murder he did not commit. One witness to the crime identified him in a lineup (half-brothers would be expected to show some resemblance, but he was unaware of his half-brother). At the time DNA analysis did not exist as it does today. Sets of enzymes in his blood, blood type and the witness testimony were enough evidence to get him to sign a plea agreement. He was convicted and sentenced to life without parole as part of the plea agreement. Flash forward 20 plus years when we have modern DNA analysis and ancestral DNA analysis. There are “projects” where lawyers strive to use modern science to correct bad arrests and convictions using modern forensic DNA analysis and archived DNA samples remaining from former crime scenes. Grandson A’s DNA proves to be only about a 23% match with the crime scene tissues suggesting that perhaps an aunt, uncle or half sibling committed the murder. But there are no known living blood-line aunts or uncles. The crime scene samples were compared to data in the databases of ancestral DNA data. 

An 11% match is found in what initially seemed to be an un-related family. Grandson C had submitted DNA for a family DNA analysis. The only living relatives of Grandson C was his elderly mother (Woman Beta, who married into the family tree) and a cousin he hardly knew. Grandson C was unaware he had another cousin, Grandson A. He told investigators he thought his cousin Grandson B now lives in NYC. NYC Law Enforcement were familiar with Grandson B because of a number of minor criminal arrests. Investigators locate this cousin (Grandson B) in NYC and collect a cigar he tossed on the street. There is no expectation of privacy for data collected from littering a cigar. DNA on the cigar is a 100% match to the crime scene DNA from decades before. It took a while, but the courts overturned the original conviction and Grandson A is released after serving 20 years for a murder committed by his unknown half-brother. Many similar cases have used even lesser shared DNA levels (2^nd and 3^rd cousins) to narrow down lists of probable suspects and have led to successful cold case closures.