Portland police said the man accused of stabbing three men who tried to protect Muslim women from his racist slurs on a train could be a "domestic terrorist”.
Jeremy Christian, 35, will appear in court this week for slitting the throats of two men and stabbing a third on a train after he verbally attacked two women, one of whom was wearing a hijab.
Two of the men died and another was wounded.
"It's too early to say whether last night's violence was an act of domestic terrorism or a federal hate crime,” Renn Cannon, the special agent in charge of the FBI office in Portland, said.
The stabbings came hours before the Muslim celebration of Ramadan began, a month of prayer, reflection and fasting.
Christian was charged with two counts of aggravated murder and one count of attempted murder, as well as two counts of second-degree intimidation and being a felon in possession of a restricted weapon, relating to his previous felony convictions of robbery and kidnapping in 2002.
Federal prosecutors are still deciding whether to add federal hate crime or civil rights charges to the counts.