Alleged Colorado shooter James Holmes reportedly sent a warning package to a psychiatrist at his former university with a notebook and drawings of his plans to massacre people.
Holmes, 24, is accused of shooting 12 people dead and wounding 58 more at a cinema on Friday in Aurora, outside Denver, as young moviegoers packed the first midnight screening of the latest Batman film, The Dark Knight Rises.
There were conflicting reports about whether the package was received in time for the massacre to be averted. Officials remained tight-lipped on Wednesday on reports that it had lain unopened in a university mailroom for days.
Fox News, quoting an unnamed law enforcement source, said the parcel, with Holmes' name written in the return address box, arrived at the University of Colorado on July 12 but sat unopened until days after the July 20 massacre.
"Inside the package was a notebook full of details about how he was going to kill people," the law enforcement source said. "There were drawings of what he was going to do in it - drawings and illustrations of the massacre."
Those drawings included some of gun-wielding stick figures shooting other stick figures, the report said.
However, a second law enforcement source quoted by Fox News said the authorities had been unable to confirm that the package had arrived before the killings occurred. The Denver Post, meanwhile, cited university officials as saying it had arrived on Monday, days after the shooting.
A police source told NBC News that Holmes had tipped them off to the package and told them to look for his name in the return address.
A report also surfaced that the suspect, who is expected to be charged with 12 murders and 58 attempted murders at his next court appearance on Monday, bought a high-powered rifle hours after failing a key oral exam.
Awarded a special grant by the government for his neuroscience studies, Holmes suddenly dropped out of the program with no explanation three days after failing the June 7 exam, ABC News reported.
Officials are unable to comment publicly on any of these matters because of a strict gag order imposed by the judge overseeing the case.
The first funeral of a massacre victim took place on Wednesday, as President Barack Obama told an event in New Orleans that he would pursue "common-sense" measures to keep guns out of the hands of mentally ill people.
In a speech to the National Urban League said he believes that even most gun owners would agree "that AK-47s belong in the hands of soldiers, not in the hands of children".
"I believe the majority of gun owners would agree we should do everything possible to prevent criminals and fugitives from purchasing weapons. And we should check someone's criminal record before they can check out a gun seller.
"A mentally unbalanced individual should not be able to get his hands on a gun so easily. These steps shouldn't be controversial. They should be common-sense."
The gunman in last week's movie theatre shooting gained access via a fire exit shortly after the film began and threw two canisters of noxious gas into the auditorium, witnesses said.
After firing one round directly into the air with a pump-action shotgun, he began shooting people at random with a military-style assault rifle capable of dispatching 50 to 60 rounds a minute.
Authorities say Holmes - who had painted his hair reddish orange - claimed he was the Joker, Batman's sworn enemy in the comic book series that inspired director Christopher Nolan's film trilogy, which features British-born actor Christian Bale as "the caped crusader".
The suspect gave himself up outside the cinema, still clad in the body armour witnesses described the gunman wearing.