(CNN)For more than four decades, one California police department employed every method available in its search for the killer of a 57-year-old apartment manager.
Authorities tracked down the suspect who killed a woman in 1973, but he's been dead for more than two decades
But by the time technology caught up, the suspect in Naomi Sanders' killing had died.
"As you can imagine, over that 46 years, many family members directly affected by the loss of Naomi have also passed, and, unfortunately they cannot be afforded the truth as to what happened," a statement from the victim's family said.
"Those of us who do remember the stories of Naomi's life and untimely death can now feel closure thanks to the determination and teamwork of the Vallejo Police Department and partnering law enforcement agencies."
Sanders was found dead in her apartment in 1973, the Vallejo Police Department said. She had been sexually assaulted and strangled, police said.
Authorities were able to collect DNA from her clothing in 2014 and two years later ran it through a California database that would flag any family ties.
"The search expanded to states in the US who would compare known offender databases for familial DNA, with negative results," police said.
The break in the case came another two years after that, with a combination of DNA analysis and family tree research that has helped solve cold cases like that of the Golden State Killer.
By collecting his son's DNA, authorities confirmed the suspect was Robert Dale Edwards, who was 22 years old at the time of the crime.
He died of a drug overdose in 1993. His criminal history included assault, theft, DUI, domestic violence, assault with a deadly weapon and attempted murder, police said.
Police said he had been a coworker of Sanders.
"May Naomi now rest in peace," Sanders' family said.