James E. Holmes, 24, is likely to face charges of first-degree murder -- an offense that carries a possible death penalty, if he is convicted -- in the shooting deaths, given allegations over the weekend by police that there is evidence to suggest "calculation and deliberation" in the rampage.
Holmes is being held in connection with the early Friday morning shootings that left 12 dead and 58 wounded, and the subsequent discovery of his booby-trapped apartment, which authorities believe he rigged before leaving for the Century Aurora 16 multiplex.
Authorities have been tight-lipped about a possible motive in the case, and police spokesman Frank Fania told CNN late Sunday that Holmes has been uncooperative with investigators and requested an attorney.
Arapahoe County public defender James O'Connor has been assigned to the case. The Colorado Judicial Department declined to say whether Holmes requested a public defender. A telephone call by CNN to O'Connor's office was not immediately returned.
Holmes' court appearance will come a few hours before his family is expected to break their silence with a statement.
The family, which lives in San Diego, has not spoken publicly since the allegations against Holmes. They issued a short statement Friday saying they did not wish to be disturbed "at the time of this tragic event."
Lisa Damiani, an attorney representing the family, told CNN the statement would be made at her San Diego office.
Over the weekend, Aurora Police Chief Daniel Oates told reporters that there was "evidence of, I think, some calculation and deliberation."
Holmes received many deliveries over the past four months to his home and work addresses, which police believe begins to explain how he got his hands on some of the materials used in the attack and those found at his apartment, Oates said.
Meanwhile, the University of Colorado School of Medicine, where Holmes enrolled in 2011 as a doctoral candidate in its neuroscience program, was investigating whether Holmes received any of the alleged shipments while working as a research assistant at the Anschutz Medical Campus in Aurora.
University spokeswoman Jacque Montgomery would not comment on reports that authorities were looking into whether Holmes allegedly used his position to obtain materials used to booby-trap his apartment.
As of late Sunday, at least 17 people remained hospitalized -- eight in critical condition -- in five area hospitals.
During a visit to Aurora on Sunday, President Barack Obama met with survivors and the families of those killed, and thousands of residents gathered in the city for a prayer vigil that drew state and local officials.
"I confessed to them that words are always inadequate in these kinds of situations, but that my main task was to serve as a representative of the entire country and let them know that we are thinking about them at this moment, and will continue to think about them each and every day," Obama told reporters after the meeting at the University of Colorado Hospital.
"It reminds you that even in the darkest of days, life continues and people are strong and people bounce back and people are resilient," the president said, after describing the recovery of some victims. "Out of this darkness, a brighter day is going to come."
Though much attention has been paid the past couple of days to the "perpetrator of this evil act," that spotlight will fade, leaving behind just the good memories of those affected by the tragedy, he said.
Aurora is bracing for another emotional week as families begin making funeral arrangements.
It was not immediately known when the coroner would release the bodies, though it was expected to occur early this week.
It also became clear that more people may have been killed if the gunman's semiautomatic rifle had not jammed.
One survivor, Josh Nowlan, suffered gunshot wounds, but said he is happy just to be alive. He wouldn't be, he said, if the gunman had continued to fire the weapon.
"I know I wouldn't be here. If that gun did not jam, I am full certain that I probably would not be here," he said from his hospital bed Saturday.
A law enforcement source, who spoke Sunday with CNN on condition of anonymity, said the rifle jammed because of a problem with the 100-shot magazine feeding it.
The military-style AR-15 had a separately purchased drum magazine, which can have trouble feeding bullets into the firing chamber if the gun is fired rapidly, the source said.
Investigators say the rifle was one of three guns used by the suspect, along with a shotgun and a .40-caliber pistol.