The suspect in the Aurora cinema shooting made threats and was banned from campus for failing an exam, prosecutors say.
They made the accusations about James Holmes in court on Thursday, as they tried to convince a judge to let them see records from the university where he had been a graduate student.
Holmes is accused of killing 12 people and wounding 58 others in the July 20 shooting during a screening of Batman.
They also claim professors had urged Holmes to get into another line of work before the shooting. Prosecutor Karen Pearson did not disclose where their information came from.
But defence lawyer Daniel King objected to the release of the records, calling the prosecution's request a "fishing expedition".
Holmes is a former neuroscience doctoral candidate at the University of Colorado.
Prosecutors want to see copies of 100 pages of non-medical education records subpoenaed by prosecutors and turned over last week by the school to Arapahoe County district judge William Sylvester.
Defence solicitors are seeking to suppress the subpoena and have asked that nobody, even Sylvester, examine the documents.
Prosecutors said in court that they need the documents to gain access to a notebook reportedly containing violent descriptions of an attack.
The notebook was reportedly in a package sent to university psychiatrist Lynne Fenton.
Mr King has said the notebook is protected by a doctor-patient relationship.
He said Holmes is mentally ill and sought Ms Fenton for help with that illness.
Ms Fenton is expected to testify at a hearing on August 30.
