The homeless man accused of killing Shoreline Community College professor Troy Wolff in an unprovoked knife attack Sept. 13 in Pioneer Square pleaded not guilty Monday to charges of first-degree murder and attempted first-degree murder.

Donnell D. Jackson, 44, said nothing during his brief arraignment in King County Superior Court.

He is accused of attacking Wolff’s girlfriend, Kristin Ito, and then killing Wolff when he intervened. The couple had just left a Seattle Sounders soccer match and were walking near Third Avenue South and South Jackson Street around 10:30 p.m. when they were randomly attacked by the armed stranger, police said.

Wolff, 46, died from his injuries the next day. Ito has been released from the hospital.

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Jackson is being held in the King County Jail in lieu of $2 million bail.

According to charging papers, Jackson claims to suffer from schizophrenia and is homeless. During an earlier hearing, public defender Maureen McKee said Jackson “suffers from an extreme mental illness.”

Jackson told detectives he arrived in Seattle about six months ago and has been off his medication for the past four months. It’s unclear why he came to Seattle, violating probation in California after an arson conviction.

His brother, Derrick Jackson, suspects he came here to try to re-establish contact with the mother of his young daughter, even though he and his former girlfriend “aren’t on good terms” and she wouldn’t let him see the baby, he said.

However, a relative of the woman said that Jackson’s former girlfriend had no idea he was now living here.

Information from Seattle Times archives is included in this report.