PORTLAND, Ore. (Reuters) - An Oregon grand jury on Tuesday returned a 15-count indictment against an ex-convict accused of harassing two African-American girls, one wearing a Muslim head scarf, then stabbing three men who intervened, killing two of them, aboard a Portland commuter train.

A convicted felon, Jeremy Christian, 35, accused of fatally stabbings two Good Samaritans who tried to stop Christian from harassing a pair of women who appeared to be Muslim, shouts during an appearance in Multnomah County Circuit Court in Portland, Oregon. REUTERS/Beth Nakamura/Pool

The suspect, Jeremy Christian, 35, who served time for a 2002 armed robbery conviction, was initially charged in a criminal complaint last week with nine felony counts from the bloody May 26 incident.

The indictment contains five additional counts and spares prosecutors the procedural step of having to present their case to a judge in a preliminary hearing to show they have sufficient cause to proceed to trial.

Christian is due to appear in court on Wednesday for an arraignment on the charges - two counts of aggravated murder, one count of attempted murder and multiple counts of assault, unlawful use of a weapon, intimidation and menacing.

Christian is accused of yelling racial and ethnic epithets at two teenage girls, both black and one wearing traditional Muslim dress, before several fellow passengers stepped in to confront him.

His tirade, according to an affidavit filed by prosecutors in the case, included the comments: “I don’t care if you are ISIS” - an apparent reference to Islamic State - and “Free speech or die.”

Prosecutors say Christian then pulled out a knife and slashed three men in their necks before fleeing the train when it stopped. One victim stumbled to his death on a station platform and another died in the rail car where he was stabbed. The third wounded man survived.

Christian was arrested a short time later and jailed without bond in the attack, which the FBI has been investigating as a possible federal hate crime. The Southern Poverty Law Center has reported finding “racist and other extremist” ideology posted on Christian’s Facebook account.

The attack became an undercurrent in dueling rallies staged in Oregon’s largest city on Sunday by supporters of President Donald Trump and counter-demonstrators who said his divisive political rhetoric was encouraging acts of racial and ethnic hatred.

Christian was said by anti-Trump activists to have taken part in a previous pro-Trump rally in east Portland in April, although sponsors of that protest denied he was part of their movement.

Prosecutors say Christian confessed to the train stabbings in a profanity-laced rant recorded in the back of a police vehicle after he was taken into custody.

In his initial appearance before a judge four days after the attacks, he entered the courtroom shouting, “Free speech or die, Portland ... This is America - get out if you don’t like free speech.”