By Keith Coffman

CENTENNIAL, Colorado (Reuters) - Accused Colorado shooter James Holmes, charged with murder over a shooting rampage last month at a movie theater in a Denver suburb, has a "mental illness" and tried to get help before the shooting, his defense attorney said in court on Thursday.

Holmes, who is accused of opening fire at a midnight screening of "The Dark Knight Rises" in the suburb of Aurora, was present in a hearing in which a judge weighed a request by 20 media organizations to unseal documents related to his case.

During the hearing, Holmes' public defender, Daniel King, repeatedly made references to his client's unspecified mental illness.

"He tried to get help with his mental illness," King said of his client, who appeared in court wearing maroon prison garb and shackled at his hands and ankles, with his dyed hair fading to pink in some places from its original reddish-orange.

Prosecutors charged Holmes, a 24-year-old former neuroscience graduate student at the University of Colorado, last week with 24 counts of first-degree murder and 116 counts of attempted murder over the rampage in which 12 people were killed and 58 others wounded.

Holmes, who appeared unshaven, seemed alert but disinterested in his third appearance in a Colorado courtroom since the July 20 mass shooting in the crowded theater. He mostly stared straight ahead and did not talk to his lawyers.

At one point during the hearing, a woman seated in the courtroom jumped up and said she had "information vital to the defense" of Holmes, and that defense attorneys would not speak with her. The judge had her escorted out of the hearing by deputies.

Judge William Sylvester said he would consider a request by news organizations to unseal documents detailing the murder case against Holmes, and would issue a written ruling later.

Lawyers representing some 20 news organizations went to court on Thursday seeking release of the court papers, saying in a written motion that sealing them "undermines our nation's firm commitment to the transparency and public accountability of the criminal justice system."

In the motion, lawyers for the media outlets, including The New York Times Co., The Associated Press, The Denver Post, and CBS News, argued that the U.S. Constitution and state case law requires a presumption of openness. Thomson Reuters is not a party to the motion.

"Absent disclosure of the factual basis for the issuance of a warrant, the public cannot properly assess the propriety of the government's conduct," the motion said.

Both prosecutors and defense lawyers objected, saying that it was too early to open the file because the investigation was still ongoing.

"The harm, judge, is very real with the release of the file at this point," defense attorney Daniel King said.

Media lawyer Steven Zansberg argued in court that the decision to close the bulk of the file made it difficult for the public to understand what happened during the shooting, and why.

Judge Sylvester said he would issue a written ruling later on the issue. Holmes is being held without bond and in solitary confinement at the Arapahoe County jail.

(Writing by Mary Slosson and Dan Whitcomb; Editing by Cynthia Johnston and Anthony Boadle)