Forensic genealogy solves 1984 cold case murder of Traci Hammerberg in Ozaukee County

PORT WASHINTON, Wis. (CBS 58) --  A nearly 35-year cold case is solved.

On Tuesday Oct. 22, the Ozaukee County Sheriff announced they have finally figured out who murdered 18-year-old Traci Hammerberg in the Town of Grafton back in 1984.

Sheriff Jim Johnson said Philip Cross sexually assaulted, strangled, and bludgeoned Hammerberg to death after she left a party in Port Washington in December 1984.

Sheriff Johnson said Cross was not one of their initial suspects. He said Cross and Hammerberg used to ride the same bus to school. He believes the two ran into each other that night after Hammerberg left a party.

Cross, who was 21-years-old at the time, left her body in the town of Grafton.

“Philip Cross had a volatile temper and was known to act violently when he didn’t get his way,” Sheriff Johnson said.

For nearly 35 years, investigators poured over the evidence and interviewed hundreds of witnesses, but no arrests were made.

In March 2019, investigators reached out to an FBI forensic genetic genealogy team out of Los Angeles who helped them crack the case.

“Those partnerships were key to solving this case,” Wisconsin Attorney General Josh Kaul said.

The sheriff said investigators used software to build the genetic genealogy of the suspect.

From there, they were able to identify a second cousin of the suspect and created family trees that led them to Philip Cross.

Cross, they learned, died in Milwaukee in 2012 from a drug overdose.

“We had mixed feelings on it,” Sheriff Johnson said. “I wanted him to face greater justice. He stole Traci’s life. “