(CBS) — The Cook County Sheriff’s office has identified another victim of the notorious serial killer John Wayne Gacy: a 16-year-old runaway from Minnesota.

Chicago News From WBBM-TV, CBS Chicago

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James Byron Haakenson was believed to have been killed in August 1976.

Haakenson’s family received the grim news from a Cook County investigator this week, WBBM’s Steve Miller reports.

James Byron Haakenson (courtesy: Cook County Sheriff’s Department)

“It’s not every day you heard this: A monster murdered your brother. It’s just not an everyday, normal conversation that you have with a detective from a different state who tells you this awful news.”

Lorie Sisterman is the Haakenson’s sister. Her DNA helped identify her brother’s remains. The DNA was submitted after someone in the family wondered if James had been a Gacy victim.

Sisterman, the oldest sibling, said the father of the family drank and wasn’t always around. Her brother was a troubled youth and ran away to Chicago at the age of 16

She remembers a conversation with another sibling around that time.

“And he said something like, ‘Jimmy’s wearing makeup.’ And I’m like, ‘What?’ So starting to dabble, maybe, in the gay lifestyle. But all of us not understanding it.”

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Jimmy Haakenson called his mother from Chicago on August 5, 1976.

Then, no word for 40 years.

This week, a Cook County Sheriff’s detective went to Minnesota to tell the family the news.

“We talked. And then he says, ‘I regret to inform you that… yes…’ A couple of people burst out crying. And all I could say was, ‘Wow,” Sisterman says.

Does she feel any sense of closure?

Sisterman, who describes herself in a fog, replies: “I don’t know what that feels like.”

There are still six unidentified victims of serial killer Gacy, who was executed in 1994.  It had been five years since his last victim was identified.

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Vintage snapshots of James Byron Haakenson, taken when he was 12. (courtesy: Lorie Sisterman)