Authorities confirmed Monday that a man who died in a thundering explosion last week on Mt. Hood was the Northeast Portland resident whose car was found nearby and that he had committed suicide.

Jeffrey Rodger Williams, 24, died around 6:30 a.m. Thursday on U.S. Forest Service land next to U.S. 26 six miles east of Welches. His car, a 2002 Ford Focus, was parked next to the highway and authorities believed he was the person who died in the blast based on circumstantial evidence.

"We were lucky enough on Friday to find fingerprints and we had enough of the hands to do a fingerprint analysis so we did not have to go to DNA (analysis)," said Dr. Karen Gunson of the Oregon Medical Examiner's Office.

"It confirmed it is Jeffrey Williams, the person we thought it was," Gunson said.

Gunson ruled the death a suicide, said U.S. Forest Service spokeswoman Laura Bain Pramuk.

Initially the Forest Service, FBI and U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives investigated the case because it was on federal land. They determined that it was not a case of homicide.

Federal authorities believe the blast was caused by a "substantial" amount of a material that target shooters use to make exploding targets.

Pieces of a gun were found at the scene, Pramuk said.

The explosion created a crater 10 feet across and 2 feet deep.

Mark Walter, 21, a roommate, said he'd last seen Williams on Wednesday afternoon. "Everything seemed normal," he said.

Walter said he couldn't understand what had happened. "I'm just as confused about the whole thing," he said.

Walter said he met Williams in 2008 at a summer camp in Corbett. He described him as a computer whiz who excelled with technology.

"He loved his jokes, but he loved serving others," Walter said. "He loved helping."

Staff writer Rob Davis contributed to this report.

-- Steve Mayes

503-294-5916; @ocmayes