A judge is weighing the evidence in the Colorado theater shootings and is expected to decide by Friday over ordering a trial for James Holmes on more than 160 counts of murder and attempted murder.

Judge William Sylvester will consider the case prosecutors made in a preliminary hearing that ended Wednesday.

Prosecutors said Holmes spent weeks preparing for the attack, amassing guns and thousands of rounds of ammunition. Prosecution witnesses described the hellish scene inside the suburban Denver theater on July 20, where 12 people were killed and 70 were injured.

Defense lawyers didn't call any witnesses for the hearing but again raised the issue of mental health. They have told the judge Holmes suffers from a mental illness.