Washington, Aug 10 (IANS): James Holmes, the suspect in Denver's midnight movie theatre shooting incident in the US state of Colorado, is "mentally ill", his attorneys have said.

Twelve people were killed and 58 injured in the July 20 attack.

The attorneys said they have not "begun to assess the nature or depth of his mental illness", and presiding Judge William Sylvester said he would soon rule to release a number of documents to the public that had been sealed by a gag order, Xinhua reported.

Holmes, a 24-year-old former Ph.D. student at the University of Colorado, was in court for the third time Thursday.

He glanced around the packed courtroom briefly after sauntering into court wearing a maroon jump suit and leg chains. His unkempt, orange-dyed hair now has a shock of dark hair protruding from its top, and his sideburns have grown bushy and brown.

Defence attorney Daniel King blasted the media, calling for continued sealing of all court documents, and demanded the return of a "package of information held by the prosecution that he said will help assess Holmes' "mental illness", the first admission of Holmes' mental condition.

All sides, including Holmes, will appear in court in one week when Arapahoe District Court Judge William Sylvester will decide whether or not the package has privileged information between Holmes and his University of Colorado psychiatrist Dr. Lynne Fenton.