Accused Colorado theater gunman James Holmes, who could be sentenced to death if convicted of killing 12 moviegoers last summer, entered a plea of not guilty by reason of insanity on Tuesday.
It was accepted by Arapahoe County District Judge Carlos Samour Jr. during a 90-minute hearing that capped months of legal wrangling over the consequences of an insanity defense.
The new plea, which replaced a standard not-guilty plea entered in March, requires prosecutors to prove Holmes was mentally capable of knowing right from wrong at the time of the alleged crime in order to win a conviction.
The decision to mount an insanity defense also poses potential new pitfalls for the defense, opening Holmes to possible self-incrimination because he must submit to a court-ordered psychiatric examination that might unearth damaging statements.
Legal experts say juries have typically shown reluctance to accept an insanity defense.
Holmes, 25, is charged with multiple counts of first-degree murder and attempted murder in connection with the July 2012 shooting spree in a suburban Denver multiplex during a midnight screening of the Batman film "The Dark Knight Rises."
The rampage ranks as one of the deadliest mass shootings in U.S. history, and along with the massacre of 20 children and six adults last December at Sandy Hook Elementary School in Connecticut, helped reignite a national debate over gun control.
In addition to the 12 moviegoers slain in the theater shooting, 58 others were wounded by gunfire and another 12 suffered various other injuries in the ensuring pandemonium.
Holmes, seated with his lawyers, said little during Tuesday's proceedings, but he appeared attentive and answered "no" when the judge asked him whether he had any questions about the implications of his new plea, entered on his behalf by defense attorney Tamara Brady.
Holmes' attorneys had argued that an aspect of the state's insanity law compelling a defendant to divulge information uncovered in a mental evaluation violates his constitutional rights. But Samour upheld the law last week.
Prosecutors are seeking the death penalty for the former University of Colorado-Denver graduate student if he is convicted in a trial currently scheduled for February 2014. A major pretrial hearing is expected in August.
Public defender Daniel King said in court last month that defense psychiatrists had obtained a complete diagnosis of an unspecified mental illness from which Holmes has suffered.
Twice since his arrest, Holmes has been hospitalized, his lawyers said, once for apparent self-inflicted head injuries and a another time for being in immediate need of a psychiatric evaluation.
Also during Tuesday's hearing, the judge ordered that prosecutors be permitted to examine the contents of a package Holmes sent to a University of Colorado, Denver psychiatrist, Dr. Lynn Fenton, who had treated him prior to the rampage. The parcel was delivered to a university mailroom two days after the killings.
A notebook included in the package possibly might have contained details of a planned massacre. Holmes' lawyers have argued the package was protected by doctor-patient privilege. But the judge ordered the parcel turned over to prosecutors by next Monday.
Fenton has testified she treated Holmes more than a month before the shooting and that her professional relationship with him ended in mid-June of that year. Police affidavits in the case said Fenton advised campus authorities in June that Holmes was having homicidal thoughts.
Defense attorneys submitted numerous pre-trial pleadings that were made public on Tuesday, including one seeking a change of venue on grounds that pretrial publicity could prejudice a jury. They also asked the judge to sequester the jury.
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