James Holmes faces 152 charges over the July shooting at a midnight premiere of the latest Batman film. Twelve people were killed and five injured. His lawyers argue he is mentally ill.
Newly-released documents said the threat was the reason the University of Colorado revoked Holmes’s access to campus. The name of the professor has been blacked out.
Prosecutors said the professor reported the threats to the university, and Holmes was denied access to campus “as a result of these actions”.
In other documents, defence lawyers said the prosecutors’ allegations are false, based on university statements.
The university has said Holmes was denied access to non-public parts of the campus because he had withdrawn from school.
Defence lawyers said Holmes sought the help of a university psychiatrist before the shooting, raising the possibility that Holmes will plead not guilty by reason of insanity.
In court, prosecutors raised the prospect that Holmes was angry at the failure of a once-promising academic career and stockpiled weapons, ammunition, tear gas grenades and body armour as his research deteriorated and professors urged him to get into another profession.
After the shooting, Holmes’ apartment was found rigged with explosives.
Chief deputy district attorney Karen Pearson said Holmes failed a key oral exam in June, was banned from campus and began to voluntarily withdraw from the school.