The accused had pleaded insanity.
Accused Colorado theater gunman, James Holmes, who could face execution if convicted of killing 12 moviegoers last summer, entered a plea of not guilty by reason of insanity on Tuesday.
The presiding judge, Carlos Samour, accepted his plea.
Mr. Holmes, 25, is charged with multiple counts of first-degree murder and attempted murder.
He is accused of killing 12 people and wounding dozens more in a gun rampage inside a suburban Denver cinema during a midnight screening of the Batman film “The Dark Knight Rises” last July.
Mr. Holmes, seated with his lawyers, said little during the latest proceedings in Arapahoe County District Court, but he appeared attentive and answered “no” when the judge asked him whether he had any questions about the ramifications of his plea.
The judge, Carlos Samour Jr., had delayed ruling on whether to accept such an insanity plea until legal questions surrounding the matter were resolved.
Among those issues was a challenge to the state’s insanity-defence law by public defenders.
They argued that a provision of the statute that requires a defendant mounting an insanity defence to submit to an examination by court-appointed psychiatrists is unconstitutional.
Compelling a defendant to divulge information that could be used against him at trial and at sentencing violates his right against self-incrimination, they argued. But, the judge upheld the law last week, setting the stage for Tuesday’s hearing.
Prosecutors are seeking the death penalty for the former University of Colorado-Denver graduate student if he is convicted.
Public defender, Daniel King, said in court last month that defence psychiatrists had obtained a complete diagnosis on Mr. Holmes’ mental illness.
Twice since his arrest, Mr. Holmes has been hospitalized, his lawyers said, once for apparent self-inflicted head injuries and again when he was held in restraints in a psychiatric ward.
At a preliminary hearing in January, before a judge ordered the defendant to stand trial, investigators testified that Mr. Holmes spent months amassing firearms and bomb making materials in preparation for committing mass murder.
At the same time he was assembling his arsenal, the accused failed his oral examinations and was told by a university professor that perhaps he was not a good fit for his neuroscience doctoral programme, prosecutors said.
Also expected to be decided at Tuesday’s hearing is the issue surrounding a package Mr. Holmes sent to a university psychiatrist who treated him that was delivered to a university mail room two days after the killings.
A notebook included in the package sent to Dr Lynne Fenton reportedly contained details of a planned massacre.
Mr. Holmes’ lawyers have argued that the package is protected by physician-patient privilege and should not be turned over to prosecutors.
Defence attorneys submitted numerous pre-trial pleadings that were made public on Tuesday, including a notice to the judge that they plan to seek a change of venue for the trial on grounds that pretrial publicity could prejudice the jury.
They also asked the judge to sequester the jury.