Keith Srakocic, Associated Press
In this April 9, 2014 file photo, Alex Hribal, right, is escorted to a district magistrate to be arraigned in Export, Pa. Hribal, 17, faces a pretrial hearing Monday, June 22, 2015, and is charged with stabbing 20 fellow students and a security guard at his suburban Pittsburgh high school last year.

GREENSBURG, Pa. — A teen charged with stabbing 20 fellow students and a security guard at his suburban Pittsburgh high school thought he was being controlled by the deceased Columbine shooters, a defense psychiatrist testified Monday.

A judge must decide whether to try 17-year-old Alex Hribal in juvenile or adult court for the April 2014 rampage at Franklin Regional High School in Murrysville, Westmoreland County, about 15 miles east of Pittsburgh. All of the stabbing victims survived, though four of the students were critically injured and hospitalized for weeks or months.

Some victims were expected to testify later at Monday's hearing, the primary purpose of which is to determine whether Hribal will continue to be tried as an adult, and thus face decades in prison if convicted, or as a juvenile meaning he must be released from supervision or incarceration when he turns 21. Hribal will be 18 in October and his defense attorney acknowledges the boy committed the attacks, using two 8-inch kitchen knives sneaked into school that morning.

Dr. Christine Martone, a defense psychiatrist, said Hribal believed he was being "egged on or controlled by Dylan Klebold and Eric Harris from hell."

The defense experts said Hribal was fascinated with the April 1999 massacre at Columbine High School in Colorado. Klebold and Harris killed themselves after killing 13 others and Hribal carried out his attack on April 9, Harris' birthday, after realizing school would be out on his preferred target date, April 20, 2014, the 15th anniversary of Columbine.

The defense experts contend Hribal was psychotic and severely depressed when he attacked the others. He expected to be killed by police, they said — but now that his mental issues are being treated by medicine and counseling, all agreed he's no longer suicidal and unlikely to do something similar.

"I can't give you a number, but there is a very low risk here," Martone testified. "What fueled this act was mental illness, not anti-social behavior."

Dr. Alan Axelson, the psychiatrist who has continued to treat Hribal while he's in a county juvenile detention center, said Hribal was "driven by suicide" — an urge he no longer has.

The doctors said the slightly built boy had difficulty relating to his peers, and sometimes felt unjustifiably threatened or offended by them. Hribal told police he stabbed the victims because he felt they were "hypocrites," but is now remorseful and considers his own behavior hypocritical for judging the victims without justification, Bruce Chambers, another psychologist testified.

Westmoreland County District Attorney John Peck wants the teen tried in adult court and said he planned to call victims and some of their parents as witnesses later Monday.

Those spectators packed the courtroom Monday, where Hribal's parents sat in the gallery behind Hribal. Dressed in a white shirt and tie, Hribal chewed and picked at his fingernails and didn't react to most of the testimony, though he smiled when Peck noted that the slightly built teen as grown some while incarcerated, and when the former director of the juvenile detention center testified about the relationship he developed with Hribal.

Common Pleas Judge Christopher Feliciani must decide whether Hribal is more likely to be rehabilitated in the juvenile system than not, though he must also consider whether it's safe to release Hribal from court supervision in less than three-and-a-half years.

Martone said Hribal told her "he should be in therapy the rest of his life" and Peck suggested, in questioning the witnesses, that there's no guarantee Hribal won't hurt others if he's freed at 21.