James Holmes, the man suspected of shooting 71 people in a Colorado movie theater on Friday, appeared in court Monday morning.
With his hair dyed orange and outfitted in a jumpsuit, Holmes listened as Judge William Sylvester advised him of his rights. He was relatively inexpressive throughout, closing his eyes occasionally or glancing at the ground.
Holmes has been in solitary confinement at a Arapahoe County detention facility, according to a report in the Associated Press.
Holmes allegedly killed 12 people and injured 59 others during a midnight screening of "The Dark Knight Rises" on Friday in Aurora, Colorado.
Under that state's laws, prosecutors have 72 hours to file charges against the 24-year-old Holmes.
But the prosecution team, comprised of Andrew Steers, Karen Pearson, Jacob Edson and Rich Orman, requested an extended period of time to file formal charges.
Holmes will be formally charged on July 30 at 9:30 a.m.
Police have given no indication about what motivated the University of Colorado student to embark on his killing spree, but said they believe he acted alone. Officials worked through the weekend trying to defuse booby traps at Holmes' apartment, which had been outfitted with incendiary devices.
After clearing the apartment of the dangerous materials, an official told the Associated Press that police had discovered a Batman mask.