Authorities in the Milwaukee area solved the 35-year-old murder and rape of Traci Hammerberg by connecting a DNA profile to a second cousin registered in a genealogy database.
Philip Cross, a Wisconsin man who died of a drug overdose in 2012, was identified as a suspect in the 1984 cold case out of Port Washington, the Ozaukee County Sheriff's Office announced Tuesday. Traci was killed Dec. 15, 1984, after partying with her friends and leaving after midnight to walk almost four miles home.
Traci's body was found brutally beaten and partially naked in a driveway in the early morning. An autopsy determined that the 18-year-old had been raped, strangled and had her head bludgeoned with a metallic object.
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Though authorities at the time were able to compose a DNA profile from semen found on Traci's body, a suspect was never identified.
Police began looking into genealogy databases in March in the hopes that the DNA profile they created in 1985 might match with a potential relative of Traci's murderer. Investigators found a potential second cousin who could lead them to their killer.
Authorities then began to build out the cousin's family tree and began to eliminate family members from a list of suspects. Cross was identified by authorities in August as someone who could fit the profile and could potentially have been in the Port Washington area at the time.
The DNA profile obtained from semen found on Traci's body in 1984 was a confirmed match to a DNA card created for Cross during an autopsy after he died of a drug overdose in Milwaukee in 2012.
Cross would have been 21 years old at the time of Traci's death and was working the graveyard shift at Rexnord Plastics in 1984, according to the Ozaukee County Sheriff's Office. Authorities suspect that Traci, who was known to take rides when offered, was picked up by Cross after he left his work shift the night she was killed.
Police found Cross had a history of violent outbursts, as well as a history of drug use. He was described by others as someone who had a temper when he didn't get his way, once punching a hole in the wall during a fight with his girlfriend in 1983.
Authorities speculated that Traci rejected Cross' sexual advances and that the man went into a rage while he raped and killed her.
The Ozaukee County Sheriff's Office credited forensic genealogy for the break that solved Traci's 35-year-old cold case. Similar techniques recently lead to an arrest in a 2017 rape case in Pennsylvania and famously helped authorities last year find a suspect in the Golden State Killer case in California.