(CBS) — The investigation into the unidentified victims of serial killer John Wayne Gacy has led to a break in a cold case in San Francisco, after DNA evidence confirmed a 1979 murder victim there was a teenage runaway from Chicago.

WBBM Newsradio’s Steve Miller reports San Francisco homicide investigators have reopened that case, now that they know the victim was Andy Drath, whose sister submitted her DNA in 2011, thinking her brother might have been killed by Gacy.

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Willa Wertheimer, who’s 51 now, remembers the last time she saw her older brother Andy Drath.

“I was about 13 or 14,” Wertheimer said. “I didn’t memorize what age I was, because I didn’t know that was the last time I was going to see him. He was so tall. And then that was it.”

Andy had been a DCFS ward and a runaway. He made his way to San Francisco. In 1979, he died there. He was shot and his body was concealed near the ocean, but his remains were unidentified for almost 36 years; his murder unsolved.

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Cook County Sheriff Tom Dart’s investigators have been trying to identify seven of Gacy’s unidentified victims, and have asked relatives of teens who went missing around the time of Gacy’s murders to submit DNA for comparison to Gacy’s victims.

Willa Wertheimer submitted her DNA in 2011, thinking her long-lost brother may have fallen prey to Gacy.

Instead, the DNA matched the remains in San Francisco.

“It’s better knowing than not knowing,” Wertheimer said. “And it’s better understanding that he didn’t somehow get mad at me and stop talking to me. And it’s really better to know he’s not suffering somewhere. That his suffering is over.”

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Dart was scheduled to discuss the closing of Drath’s missing person case Wednesday morning at the sheriff’s headquarters in Maywood.