CENTENNIAL: Suspected Colorado gunman James Holmes made his first appearance in court Monday, orange-haired and seemingly bewildered, to face charges after one of America's worst-ever mass shootings.

Wearing a maroon prison jumpsuit, the 24-year-old Holmes stared blankly as lawyers discussed procedural arrangements with the Arapahoe County judge. He was later led out after the hearing, which lasted less than 10 minutes.

He is accused of shooting dead 12 people and wounding 58 others at a cinema Friday in Aurora, outside Denver, as young moviegoers packed the midnight screening of the latest Batman film, "The Dark Knight Rises".

Holmes is scheduled to appear in court again next Monday to face arraignment and be formally charged over the massacre, and was ordered to remain in custody with no bail allowed.

A number of family members of victims were in the court in Centennial, and stared at Holmes throughout the brief appearance. He did not return their gazes, according to CNN.

It was impossible to determine if Holmes' behavior was the result of stress, drug-induced or perhaps an act. Prosecutors are expected to seek the death penalty, although experts note that only one person has been executed in Colorado since 1976, ABC and local media reported.

Police say there is no doubt Holmes committed the atrocity. He gave himself up outside the cinema, still clad in the full body armor that witnesses described the gunman wearing as the bullets flew inside.

The gunman emerged from a fire exit after the film began and threw two canisters of noxious gas into the crowd. After firing one round directly into the air with a pump-action shotgun, he then began shooting people at random with a military-style assault rifle that could dispatch 50 to 60 rounds a minute, witnesses said.

Holmes has been held in solitary confinement since his arrest. New York City Police Commissioner Ray Kelly said Holmes had painted his hair reddish orange and claimed he was the Joker, Batman's sworn enemy.

According to media reports and at least one witness, the gunman might have killed more people had his AR-15 assault rifle not jammed.

Calls for another look at America's gun laws are mounting in the aftermath of the tragedy as it emerged that Holmes bought his four weapons legally, as well as thousands of rounds of ammunition on the Internet.

Over eight weeks he stocked up over the Internet on 6,300 rounds of ammunition: 3,000 for his .233 semi-automatic AR-15 rifle, another 3,000 for his two .22 Glocks, and 300 cartridges for his pump-action shotgun.

Police said on Sunday they had found Holmes's computer inside his booby-trapped apartment -- designed to kill anyone who entered -- which could provide crucial details about how he planned and executed the attack.

On Sunday, President Barack Obama visited Aurora, which is located just 20 miles (32 kilometers) from the scene of the 1999 Columbine High School massacre, in which two students shot dead 13 people before committing suicide.

That shooting prompted consternation in the United States and the rest of the world, but ultimately had no effect on America's gun laws which are backed by a constitutional amendment defending the right to bear arms.

During his visit to Aurora, Obama met with survivors of the shooting, telling the nation that he hugged and “shed tears” with them and relatives of the victims.

But Obama and Republican presidential hopeful Mitt Romney faced pressure on Sunday from New York Mayor Michael Bloomberg -- one of the few high-ranking US politicians that openly favors gun control -- to take action.

“This really is an enormous problem for the country, and it's up to these two presidential candidates,” Bloomberg said on the CBS show Face the Nation.

“They've said things before that they're in favor of banning things like assault weapons.

“Where are they now and why don't they stand up?” asked Bloomberg. “If they want our votes, they'd better.”

Supporters of the right to bear arms, though, brandish the argument that if someone in the auditorium had possessed a weapon then they could have taken down the shooter and limited the carnage.

“If I had been there, I would have stopped some damage,” John Oberly, a 51-year-old rugby coach, told AFP at an Aurora gun store. “In fact if anybody had been carrying one, they may had stopped some of the damage.”