(Adds legal analysis, more background on case)
By Keith Coffman
DENVER, April 7 (Reuters) - Lawyers for the man charged with mass murder in a 2012 shooting frenzy that left 12 people dead at a Colorado movie theater have asked that his upcoming trial be moved out of the suburban Denver county where the case has been prosecuted.
Defense attorneys argued in their motion for a change of venue that James Holmes' right to a fair trial in Arapahoe County has been compromised by "pervasive media coverage" of the case locally and "the undeniable impact of the tragedy on the community itself."
Holmes, 26, has pleaded not guilty by reason of insanity to murder and attempted murder charges stemming from the July 2012 massacre at an Aurora, Colorado, cinema during a midnight screening of the Batman film "The Dark Knight Rises."
Twelve moviegoers were killed and 70 others hurt in one of the deadliest outbursts of U.S. gun violence in decades. The case made international headlines and drew especially intense news coverage in the Denver area.
Holmes' public defenders argued that the glare of publicity, including voluminous commentary and reporting on evidence ruled inadmissible at trial, would make it impossible to seat an impartial jury in Arapahoe County.
"The pretrial news coverage has been at best consistent and comprehensive," the 37-page motion said. "At worst, the media has been incessant and unrelenting."
CHANGE OF VENUE SEEN AS RARE
Jury selection is scheduled to begin Oct. 14, though Arapahoe County District Judge Carlos Samour has said that date could change.
Prosecutors have said they intend to seek the death penalty if Holmes is convicted.
Despite the high profile of the Holmes prosecution, prevailing case law favors proceeding to jury selection before a judge would entertain a request for a change of venue, Colorado defense lawyer Mark C. Johnson said.
"Filing a motion to move a trial is not unusual, but having it granted is," said Johnson, who won a venue change for a Colorado murder suspect he once defended.
Prosecutors had no immediate response to the change of venue motion, which was filed in court on Holmes' behalf on Friday and made public on Monday. But the defense said in its filing that prosecutors object to moving the trial.
Former Denver prosecutor and legal analyst Craig Silverman said juries in Arapahoe County have imposed the death penalty on convicted murderers, but asking to have the trial moved posed its own risks for the defendant.
"If venue is changed, the defense team runs some danger that it could be moved to a more conservative jurisdiction, where a conviction and death penalty is more likely," he said.
Holmes' lawyers have acknowledged that the one-time neuroscience doctoral candidate was the lone gunman who did the shooting, but they say he suffers from a chronic mental illness and was experiencing a psychotic episode when he opened fire.
In accepting Holmes' insanity plea, the judge has placed the burden on prosecutors to convince a jury that the defendant understood right from wrong when he committed the crime.
Holmes already has been declared mentally competent to stand trial - meaning he has been found capable of understanding the proceedings against him and assisting in his own defense.
But Judge Samour has ordered Holmes to undergo a second sanity evaluation after finding that an earlier examination was "incomplete and inadequate."
Separately on Monday, Governor John Hickenlooper signed into law a measure that would expand mental health professionals' duty to report threats a patient makes against "specific entities," such as a movie theater. The current statute required warnings only of threats made against people. (Reporting Keith Coffman; Writing by Steve Gorman; Editing by Cynthia Johnston and David Gregorio)