PORTLAND, Ore. (KOIN) — Investigators from Alaska and Oregon worked together to crack the decades-old murder of a 16-year-old girl in Anchorage.

Shelley Connolly was last seen in January 1978 talking with 4 men in a bar. Hours later, her body was found in a ditch along the Seward Highway, about 15 miles south of Anchorage.

Connolly had been sexually assaulted, beaten, dragged by a car and thrown down an embankment. Her fingernails were broken, indicating she might have tried to crawl back up the embankment.

An undated photo of Shelley Connonlley, who was murdered in Alaska in 1978. (Courtesy of Alaska Citizens for Justice)

Alaska State Troopers said DNA evidence collected during the autopsy was entered into a criminal database in 2003. Investigators used genetic genealogy to identify Donald McQuade, who now lives in Gresham, as a potential suspect in the case.

“In this particular case, we wielded it down to one of three brothers and then from there, we used standard investigating techniques to figure out which brother was in Alaska at the time,” cold case investigator Randy McPherron said.

McQuade was 21 years old and living in Alaska at the time of the murder.

His brother, Richard McQuade, told KOIN 6 News Gresham detectives approached them when they went to pay their water bill on August 30.

“They said ‘well we found your DNA on a cigarette butt on the ground,'” Richard said.

Richard believes police have the wrong man.

“How could he have committed this crime 41 years ago and also with a sister who says he wasn’t even in the area?” Richard said.

He said Donald has lived in Gresham since 2006 and hung out at the same bar Connolly was last seen in, but he would never have hurt her.

“I have felt and I have talked to other family members, we have never noticed that type of behavior ever in Donald,” Richard said. “If anything he might have been in the car, not at the time the crime was committed by someone.”

The victim’s mother said she never thought she would see the day when someone was arrested for her daughter’s death.

Judy Connolly says she was flabbergasted when she heard from Alaska State Troopers that McQuade had been arrested.

“Mainly disbelief,” she said. “Happiness that they found him. Sad too. 41 years, long time grieving.”

McQuade is due in court Wednesday, September 4 for the murder charge. He is expected to be extradited back to Alaska.

Watch: Alaska State Troopers press release on the arrest

The Associated Press contributed to this report.