Attorneys for the suspect in the Colorado movie theatre shootings said Thursday that their client is mentally ill and that they need more time to assess the nature of his illness.  

James Holmes' lawyers made the disclosure at a court hearing in Centennial, Colo., where news media organizations were asking a judge to unseal documents in the case.  

Holmes had the same dazed demeanour that he has had in previous court appearances.  

Attorney Daniel King made the revelation as he argued defence lawyers need more information from prosecutors and investigators.  

"We cannot begin to assess the nature and the depth of Mr. Holmes' mental illness until we receive full disclosure of all the documents," King said.  

News media organizations were asking the judge to unseal court documents and scale back a gag order that bars the university that Holmes attended from releasing details about him.  

The Associated Press and 20 other news organizations want Chief District Judge William Sylvester to unseal documents that could provide the public with details about Holmes and the massacre in Aurora on July 20.   

The shooting during a midnight showing of the latest Batman movie left 12 people dead and injured 58 others. Holmes, a 24-year-old former PhD student at the University of Colorado, is charged with multiple counts of first-degree murder and attempted first-degree murder.  

Arapahoe County prosecutors argue releasing documents could jeopardize their investigation. Holmes' attorneys want to ensure he receives a fair trial.  

Sylvester's order sealing documents includes the case file, which makes it impossible for observers to understand prosecution and defence arguments on motions that are referenced by number only.  

Sylvester on July 23 also issued a gag order that bars officials at the University of Colorado from responding to public records requests concerning Holmes.  

The judge said doing so would jeopardize the county's investigation. Aurora officials have cited the order in declining to speak about the city's response to the shootings.