VALLEJO (CBS SF) — Decades after the rape and murder of a Vallejo woman, Naomi Sanders, investigators have finally closed the cold case with the help of new DNA analysis, determining the son of one of her co-workers was the killer, according to police.

On February 27, 1973, the 57-year-old Sanders was found strangled to death inside her apartment where she lived alone with her pet poodle and worked as the manager of the apartment complex.

Vallejo police detectives worked the case for many years and in 2014, forensic testing on her clothing indicated the presence of semen staining. While a DNA profile was developed, there were no matches in the database used by authorities.

Detectives continued to check the profile against new people entered into the database, and in 2016 also checked it against data banks for people related to the suspect in California and other states, with negative results.

By 2018, Vallejo detectives turned to the emerging science of investigative genetic genealogy, in which DNA is matched to public genetic genealogy databases to find relatives. After partnering with Virginia-based Parabon NanoLabs, in April 2019, a DNA genealogy analysis narrowed the search to two male leads.

Using DNA from one of these leads, detectives were able to eliminate him as being the suspect. Detectives also found the remaining lead was deceased his remains had been cremated.

However, the detectives also learned the remaining lead had a biological son who lived out of state. He was contacted and his DNA was collected, which provided the answer Vallejo police had been searching for more than 46 years.

The 2nd lead was the suspect, Robert Dale Edwards, a Vallejo resident who was 22 years old at the time of the murder. Edwards died in 1993 from a drug overdose in Napa County.

Investigators found that Edwards’ father had previously been a co-worker of Sanders. His criminal history included attempted murder, assault, theft, and domestic violence.

While Sanders had no children, she was one of ten brothers and sisters. Detectives were able to contact two of Sanders’ nieces and the family provided Vallejo police the following statement:

“The Kadinger Family is immensely grateful to the Vallejo Police Department and to everyone who worked this case for the past 46 years. 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.

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. May Naomi now rest in peace.”