A convicted sex offender pleaded not guilty Wednesday to killing an 89-year-old Oregon woman who had been missing for a week before a body believed to be hers was found in his trunk.

Timothy Mackley, 58, appeared in a Portland court and waived his right to a probable cause hearing. His court-appointed attorney, Kathleen Dunn, did not immediately respond to a request for comment.

Mackley was arrested Monday when police found a body in his car trunk during a traffic stop, Portland police Sgt. Christopher Burley said.

The body is "likely" that of Marcine Herinck, who was reported missing on Sept. 19 from her home, Burley said in a statement.

Police are awaiting confirmation on the body's identity from the Oregon Medical Examiner.

Court documents filed after Wednesday's hearing show prosecutors have charged Mackley with her murder.

Herinck, a grandmother who regularly attended church and volunteered at a thrift store, lived independently despite some memory issues, police have said.

She was brought home the evening of Sept. 18 and disappeared the following day.

Her purse was found on the kitchen floor, a cup of coffee was in the microwave, her garage and front doors were open, and the clothes she wore the night before were on her bed the day she disappeared, KGW-TV has reported, citing a family account.

Search and rescue crews spent days looking for her — making repeated pleas to the public for tips — until police on Monday developed new information that suggested foul play and pointed them in Mackley's direction, Burley said.

Based on that information, police stopped Mackley's car on and found the body, he said.

No additional details were released, and Burley did not return a call seeking further comment.

Mackley is a convicted sex offender who pleaded guilty to sexual abuse and sodomy in Multnomah County and was sentenced to prison in 1989, court records show. He was arrested in 2009 for failing to register as a sex offender, those records show.

He also has previous felony convictions in Washington state from the 1980s, according to court paperwork filed as part of his bail review.

Mackley told court officers in Oregon that he has been diagnosed with schizophrenia and bipolar disorder and lives on disability payments of less than $1,000 a month, court records show.

He volunteered driving people to Alcoholics Anonymous meetings in his spare time, he told court officers.

The most recent address listed for Mackley is less than two miles (3.2 kilometers) from where Herinck lived.

"It's been very, very troubling for us," Jeff Herinck Sr., her son, told The Oregonian/OregonLive after the hearing. "She was a great person."

A breast cancer patient support organization called Breast Friends of Oregon said on its Facebook page that Herinck came each year to the survivors' luncheon and stood proudly when recognized as the organization's longest cancer survivor.

The group will have a moment of silence for Herinck at its next luncheon, the post said.

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A previous version of this story incorrectly stated the day of Mackley's arrest. He was arrested on Monday.

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