Holmes, 24, is scheduled to be formally charged Monday in the shooting deaths of 12 people and the wounding of 58 others last Friday during a midnight showing of the latest Batman movie, "The Dark Knight Rises," at the Century Aurora 16 movieplex in Aurora, Colo.
Earlier this week, authorities seized a package Holmes sent to a psychiatrist at the Anschutz Medical Campus.
Defense attorneys filed a motion Thursday stating the package constituted a communication between Holmes and his psychiatrist, Dr. Lynne Fenton, The Denver Post reported. The Washington Post reported Fenton specializes in schizophrenia.
The Post said District Attorney Carol Chambers' response to the filing indicated police have yet to open the package. Reports earlier this week indicated the package was a notebook in which there were crude drawings of a shooting spree.
Holmes was a doctoral student in neuroscience at the university. The university last week said he was in the process of withdrawing.