PORTLAND, Ore. — Police in Portland, Oregon, are investigating whether the man charged with killing two men and wounding another on a light-rail train stabbed a man in the back earlier this year.

Portland police Sgt. Chris Burley said Friday that 35-year-old Jeremy Christian is “a main suspect” in the stabbing that happened Jan. 27 outside Voodoo Doughnut in downtown Portland.

Burley says the investigators are not releasing additional information about the case.

KPTV reported in January that Voodoo Doughnut employees called 9-1-1 just after 5 a.m. when a fight broke out between four or five homeless people. Police said the 40-year-old victim was taken the hospital with an injury that was not life-threatening. Police described him as uncooperative.

Christian has been in jail since May 26, when police say he stabbed three train passengers after going into an anti-Muslim tirade. He pleaded not guilty to aggravated murder and other charges.