A US judge ordered on Thursday that alleged cinema gunman James Holmes stand trial over the massacre that killed 12 people in Colorado last July, court documents showed.
Judge William Sylvester found that prosecutors had established there was "probable cause" to believe the defendant committed the crimes, and ordered Holmes to be arraigned in court on Friday.
"The court orders that defendant shall be bound over for trial on all counts," he wrote in a 61-page ruling posted online, listing all 166 charges against the 25-year-old.
Holmes is accused of killing 12 people and injuring at least 58 in the shooting in a midnight premiere screening of the latest Batman movie in a theater in Aurora, Colorado.
Over three days earlier this week, prosecutors called witnesses who gave harrowing accounts of the slaughter, and played 911 emergency calls in which the chaos and loud gunshot booms could be clearly heard.
Holmes' lawyers had been expected to present witnesses to bolster a case that he may be mentally unfit to stand trial. But in the end they announced they would not, and the judge adjourned the hearing Wednesday until Friday.
Shortly before the judge's trial order, Holmes' lawyers filed a motion for Friday's court appearance to remain merely a status hearing, rather than an arraignement, in which he is formally charged.
But Sylvester said the hearing, scheduled for 9:00 am (1600 GMT) Friday, "is hereby converted to an arraignment."