SAN DIEGO -- An ex-con accused of stabbing a man who was trying to break up a fight between the defendant and a teenager on a trolley must stand trial on assault, battery and other charges, a judge ruled Friday.

Exodus Bolton, 36, has been to prison three times for domestic violence and drug convictions, according to court records. He faces up to 13 years in prison if convicted, said Deputy District Attorney Oscar Garcia.

At the conclusion of a two-hour preliminary hearing, Superior Court Judge Browder Willis ruled there was probable cause to believe the defendant was guilty of the charged offenses, including mayhem, resisting arrest and making a criminal threat.

The judge did not, however, hold the defendant to answer to a hate crime allegation, saying not enough evidence was produced at the hearing to support that charge.

Garcia said he wasn't sure if prosecutors would refile the allegation.

San Diego police Detective John Morris testified that a 17-year-old -- described as a punk rocker -- became upset when Bolton, who is black, began making anti-gay slurs toward another black man on the trolley the afternoon of Oct. 17.

Bolton began yelling and spitting on the teenager when the teen said he was openly gay and didn't appreciate the defendant's comments toward the other man, Morris testified. Bolton then punched the teenager twice in the face and head and referred to himself as an "assassin," the detective said.

The teen told investigators that he saw a good Samaritan come up and push Bolton away then saw Bolton with a knife with blood on it.

Victor Mendoza ended up with two stab wounds to his left arm, the detective testified.

The detective said Mendoza told him that he thought the black man who was the initial target of Bolton's verbal attack had bumped the arm of the defendant's wife.

Mendoza said he decided to intervene when he saw Bolton punching the teenager, Morris testified.

One of the stab wounds severed a nerve in Mendoza's arm that affects the wrist and finger movement, said district attorney's Investigator Khamp Thongrivong.

According to the investigator, a woman reported that Bolton attacked her and a male friend on Oct. 14 on the trolley, pushing the friend out of his seat so he could sit next to his wife. The woman told Bolton to show some respect, and then he approached the pair screaming and yelling and slapped her friend in the face, Thongrivong said.

Bolton allegedly told the woman he had a gun and was going to kill her. She was so afraid she couldn't push the emergency button to get help, Thongrivong testified.

He said he also interviewed a woman who said she saw Bolton pull a knife out of his jacket during the Oct. 17 confrontation on the trolley.

When Bolton was fighting with Mendoza, the woman said she heard the defendant say, "I'm going to kill you," according to the investigator.

The defendant, held on $60,000 bail, will be back in court Jan. 12 for a readiness conference. Trial was set for Jan. 19.