Authorities on Monday discovered a package in a mailroom at the University of Colorado - Anschutz Medical Campus apparently sent by the alleged gunman responsible for the theater shooting that left 12 people dead and scores injured, a law enforcement official briefed on the investigation said Wednesday.

It was sent to the school's campus in Aurora, where the suspect, James Holmes, had recently dropped out of a Ph.D. program in neuroscience.

CBS News reported that the package was addressed to a psychologist at the university.

"Sources say the letter was from a pent-up Holmes to one of his professors," the news organization reported. "In it, he talked about shooting people and even included crude drawings of a gunman and his victims."

School officials said in a statement that a package discovered at the Facilities Services building on Monday had been delivered to the campus by the U.S. Postal Service that same day and was turned over to authorities within hours of delivery.

"This package prompted the building's evacuation at 12:26 p.m. and employees were allowed to return by 3:06 p.m.," the statement said.

School administrators said that Holmes had taken his preliminary examinations at the school on June 7.

A source familiar with Holmes' academic status said the 24-year-old suspect did "poorly" on the oral exam.

Three days later, Holmes initiated his withdrawal from the program.

"It's very unusual, very unusual for a student to withdraw from our program," Dean Barry Shur told reporters on Monday.

Holmes did not divulge his reason for leaving the elite program. "That area of the form was left blank," Shur said.

Meanwhile, a composite image began to emerge of Holmes as a child; his classmates at Castroville Elementary School in northern California, where he grew up, referred to him as "Jimmy."

But that picture revealed no immediate answers as to possible motive. "He was top of the class," Adam Martinez said. "He was ahead of every student academically."

Martinez added, "He got along well with everybody."

Holmes' fifth-grade teacher there said the matter has led to introspection. "It's really disturbing to be so close to something like that -- bothers you to your essence," Paul Karrer said. "And particularly, as a teacher, you're thinking, this is one of my kids. And then you also think: Could I have done anything? Or did I see anything? Did I miss anything? You know, could I have done anything to have prevented this? Did I do anything to cause this? The answer is no, but that's what you think and that's how you feel."

As of Wednesday evening, five area hospitals were still caring for 17 patients, six of whom were in critical condition.

Several of the hospitals said they would pay for the medical care of uninsured victims out of charity funds.

Holmes made his first court appearance Monday.

The man who identified himself to police as "the Joker" will continue to be held without bond. He is to be formally charged July 30.

Meanwhile, families grappling with Friday's carnage were beginning to bury the dead.

On Wednesday, a memorial service was to take place for 51-year-old Gordon Cowden, who took his two teenage children to see the midnight premiere of the Batman movie "The Dark Knight Rises." Cowden's children survived the shooting inside the Aurora theater.

Nine miles away, visitation was to take place for Micayla Medek, a 23-year-old woman who had been working toward her college degree.

Those who were wounded still face the specter of permanent injury and long recovery periods.

In Aurora, actor Christian Bale, star of "The Dark Knight Rises," visited a memorial for the dead and met Tuesday with survivors, CNN affiliate KDVR reported.

One of the victims, Carey Rottman, posted a picture of Bale visiting him in his hospital room on Facebook.