UPDATED: at 12:11 a.m., July 4, 2016

Mike Marshman, Portland's newly appointed chief of police, was the subject of an abuse allegation in August 2006 involving his stepson.

A detective in the Police Bureau's family services division investigated the complaint. Marshman did not talk to the detective investigating. No criminal charges were filed.

The bureau found the complaint "unproven'' following an internal affairs inquiry, according to Marshman.

Marshman acknowledged the inquiry, and the Police Bureau is expected to release the police report on the original complaint Tuesday. It was being ordered from archives.

The internal affairs investigation was purged after seven years, bureau spokesman Sgt. Pete Simpson said.

"It was investigated and went through the process,'' Marshman told The Oregonian/OregonLive.

The allegation included a claim that Marshman grabbed his stepson, then 16, around the neck until he couldn't breathe and threw him against a wall at their home, sources said. The physical encounter occurred after the stepson called Marshman a name, apparently upset that Marshman had blamed him for leaving a light on in the kitchen of their house, sources said.

Marshman's wife and stepson didn't file a complaint, but one was made anonymously four years later that prompted the police investigation.

The Multnomah County District Attorney's Office reviewed the investigation and declined to prosecute, citing insufficient evidence in 2006.

The stepson told police that Marshman demanded he turn the kitchen light off, and the stepson was angered that Marshman wouldn't turn the light off himself and called him a vulgar name, according to deputy district attorney Charlene Wood's decline to prosecute memo.

After he was thrown against a wall, the stepson said he couldn't speak and had a loss of breath but the pain wasn't long-lasting. He did have visible bruises on his neck the next day, which his mother at first thought were hickies. They were photographed, Wood's memo says.

Read the Multnomah County District Attorney's decline to prosecute memo

Woods wrote that "the level of injury is not sufficient for the felony charge of criminal mistreatment in the first degree'' and the two-year statute of limitations for misdemeanor charges of harassment or attempted criminal mistreatment for the alleged 2002 offense had run out.

Woods wrote that the stepson's description of what occurred fit the misdemeanor offense of strangulation, but the offense wasn't a crime in the state in 2002, when the incident happened. Strangulation became a crime under legislature passed in 2003, her memo said.

Marshman described the encounter like this: "I thought he was going to come at me, so I held him against the wall.'' Marshman said he thought his stepson was college-age, about 20 years old.

Asked if there was damage, Marshman said there was a "minor dent'' in the wall, which he described as made out of sheetrock.

He was living on Sauvie Island at the time and it occurred in their home, he said. Marshman is no longer married to the stepson's mother and has remarried. The ex-wife didn't return calls for comment. His stepson declined comment.

Marshman, a 25-year bureau veteran, said he couldn't recall what led up to the encounter but it occurred during the ending of his relationship with the stepson's mother.

"I can't remember what it was about,'' he said.

He's expected to release the detective's investigative report Tuesday and his entire personnel file.

-- Maxine Bernstein

mbernstein@oregonian.com

503-221-8212

@maxoregonian