LAKE STEVENS — A man was mowing his neighbor’s property north of Lake Stevens when a strong odor suddenly struck him.

It smelled of death. As he continued mowing, he reportedly found a woman’s body hidden under some brush.

Authorities later identified the woman found Aug. 20 as Katie McQueen, of Mariposa, California. She was 37.

Due to decomposition, the Snohomish County Medical Examiner’s Office couldn’t determine exactly how McQueen died. But she had suffered “significant trauma” to her neck, deputy prosecutor Bob Langbehn wrote in court papers.

According to murder charges filed last week, swabs taken from her wrist turned up a DNA match: Mark Downey.

Downey, 56, is familiar to local police. At the time of McQueen’s death, he was on probation after pleading guilty to molesting a girl in Mountlake Terrace. Before that, he spent nearly 18 years in prison for killing Kathy Lynn Erickson, 35, in Bellingham.

In mid-September, police went on a routine probation check to a group home for sex offenders on Smokey Point Boulevard where Downey was staying. But he wasn’t there, according to the charges.

The homeowner told investigators Downey had left three weeks earlier without any notice, the charges say. The owner thought Downey was heading to Mexico or Arizona.

Detectives learned Downey had been arrested in Mexico on Aug. 25 for investigation of violating his probation, according to court documents. Last month, he was transferred to Snohomish County.

A couple days later, he reportedly gave an extensive police interview.

Downey reported he’d gone to Mexico on Aug. 13 or 14. Detectives showed him photos of McQueen. He said he didn’t recognize her, according to court papers. He also denied having contact with any women after his release from prison because he was afraid of violating his probation.

He later changed his tune, acknowledging he’d seen her at a bus stop. In one version of his story, he said McQueen and a man approached her and she started kissing him, according to charging papers. He reported he panicked and left.

Later, Downey told detectives he gave McQueen and the man a ride to a gas station. He also said he witnessed the man stab the woman in his car, according to the charges. He claimed he freaked out and fled to Mexico out of fear of being blamed as an accessory to her killing.

In another version, he reported she attacked him with a knife, but he somehow made her stab herself in the throat because he has a black belt in martial arts, according to court documents.

In a final version, he took responsibility for killing McQueen. He reported agreeing to pay her for sex, so they drove out near the 11800 block of 84th Street NE, police said. When he couldn’t get aroused, she made fun of him.

Feeling emasculated, he took a spring-loaded knife from his pocket and stabbed her in the throat, according to the charges. He reported she bled out quickly, so he rolled her body into bushes. He said he took her clothes and shoes, and disposed of them at a Safeway in Arlington.

The next morning, he fled to Mexico, prosecutors allege.

Last week, prosecutors charged Downey in Snohomish County Superior Court with second-degree murder as well as failing to register as a sex offender. If convicted of second-degree murder as charged, Downey would face between 20¼ years and just over 28½ years in prison under state sentencing guidelines.

On Wednesday, he remained in the Snohomish County Jail with bail set at $5.5 million.

Jake Goldstein-Street: 425-339-3439; jake.goldstein-street@heraldnet.com; X: @GoldsteinStreet.