James Holmes, accused of killing 12 people in the June 20 massacre at a midnight screening of "The Dark Knight Rises" in Aurora, Colorado, was banned from campus over the threats, which local media reported were made to a professor.

Holmes had a "relationship terminated on, or prior to June 12, 2012," according to one court document that blacked out various words to conceal the person's identity.

"The relationship was terminated after the defendant made threats" towards the unidentified person, who reported them to the University of Colorado Police Department.

"As a result of these actions, university administration terminated the defendant's access privileges to all or part of the Anschutz campus," where Holmes was a neuroscience graduate student, the court document added.

Holmes has been held in solitary confinement at Arapahoe County Detention Center since the shooting, in which he allegedly threw smoke bombs into a crowded theater before opening fire, dressed in body armor and a gas mask.

He could face the death penalty if convicted, although Colorado has only executed one person since capital punishment was reinstated in 1976.

The documents released Friday also detailed legal wrangling over a notebook sent by Holmes to a psychiatrist who treated him in the months before the massacre.

Attorneys for the defendant voiced concern that media leaks about the notebook kept by Dr Lynne Fenton could jeopardize Holmes' right to a free trial.

One document recounted how "an Aurora police detective on scene fanned" through the notebook when it was first found -- before it was sealed as evidence which could be crucial in any trial.

The "disclosure of this confidential and privileged information has placed Mr. Holmes' constitutional rights to due process and a fair trial by an impartial jury in serious jeopardy," it said.

School documents are usually available under the Colorado Open Records Act, but a judge issued a rare order barring the University of Colorado Denver from release records about Holmes days after the shooting.

University officials said Holmes was in the process of withdrawing from the graduate program at the university, but had not completed the necessary paperwork.