A mental hospital says the sanity evaluation of Colorado theater shooting suspect James Holmes will take until mid-September, nearly seven weeks longer than the judge wanted.

The judge set a July 31 deadline for the Colorado Mental Health Institute to finish the evaluation and submit a report. In a letter made public Thursday, the hospital asked for an extension until Sept. 16.

The hospital cited the volume of documents the psychiatrist in charge has to review.

The judge scheduled a hearing for Tuesday to discuss how the delay will affect hearings and the trial, scheduled to start in February.

Holmes is charged with killing 12 and injuring 70 at a movie theater in July. Prosecutors are seeking the death penalty.

Holmes has pleaded not guilty by reason of insanity.