* Judge finds probable cause to believe James Holmes committed crimes
* Defense expected to seek postponement of plea at Friday's hearing
* Legal experts see insanity defense as likely (Adds details, quotes, analysis, background)
By Keith Coffman
DENVER, Jan 10 (Reuters) - A Colorado judge ordered accused movie theater gunman James Holmes on Thursday to stand trial on charges he killed 12 people and wounded dozens more in a shooting rampage at a midnight screening of a Batman movie last summer.
The ruling followed three days of emotionally wrenching prosecution testimony about the shooting, its bloody aftermath and the elaborate preparations that Holmes is accused of making for the attack.
Arapahoe County District Judge William Sylvester ruled that evidence presented during the preliminary hearing had established probable cause to believe that Holmes, 25, committed the crimes, and ordered him bound for trial on all counts.
He said Holmes, who has been described by his own lawyers as suffering from an unspecified mental illness, should continue to be held without bail.
Some legal experts say this week's proceedings left Holmes' lawyers with little choice but to mount an insanity defense for their client.
"The defense team has nowhere else to go given the obvious premeditation and overwhelming evidence against Holmes," said Craig Silverman, a former Denver prosecutor now in private practice as a trial attorney.
The former neuroscience doctoral student is charged with 24 counts of first-degree murder and 140 counts of attempted murder stemming from the July 20 rampage at the opening of "The Dark Knight Rises" in the Denver suburb of Aurora.
In addition to the 12 people who died, 58 others were wounded by gunfire and a dozen more suffered other injuries.
Prosecutors essentially charged Holmes twice for each victim, once for committing a crime "after deliberation" and again for "malice manifesting extreme indifference to human life."
The movie house rampage stands as one of the most lethal mass shootings in U.S. history and one that ranked briefly as the deadliest in 2012 - until 20 children and six adults were killed last month at a Connecticut elementary school.
DEFENSE TO SEEK POSTPONEMENT OF PLEA
Assuming Holmes enters a plea of not guilty, the prosecution will then have 60 days to decide whether to seek the death penalty. But defense attorneys who will return to court on Friday were expected to ask that the arraignment be postponed.
In documents filed on Thursday opposing a media request to allow cameras in the courtroom - as Colorado judges can permit for arraignments - Holmes' team said they were not prepared to enter a plea in the sensational case.
Holmes is accused of entering Theater 9 of the Century 16 multiplex with a ticket he bought 12 days in advance, then leaving through a rear exit minutes into the movie and re-entering moments later wearing body armor and a gas mask.
Armed with a shotgun, pistol and semi-automatic rifle, authorities say, Holmes lobbed a tear gas canister into the auditorium and sprayed moviegoers with bullets until one of his guns jammed, then surrendered to police without a struggle in the parking lot behind the theater.
Police testified that Holmes began assembling his collection of guns and ammunition two months before the shooting, scouted out the multiplex weeks ahead of time, and took photos of his arsenal and of himself posed with weapons and body armor.
Holmes had also booby-trapped his apartment near the theater with explosives, which police said he intended as a diversion to draw authorities away from the movie house while he was carrying out his assault. The bombs were later defused safely.
Officers called to the theater that night recounted a scene of shooting victims sprawled across a darkened, blood-soaked auditorium as the movie continued to play on the screen and emergency strobe lights flashed.
Holmes' lawyers made no attempt during the preliminary hearing to challenge the case laid out by the prosecution and declined to present evidence or witnesses of their own.
What few points defense lawyers did make through cross-examination appeared to be aimed at calling attention to the erratic behavior of their client.
A homicide detective acknowledged under defense questioning that Holmes tried to insert a staple into an electrical outlet while being interrogated at police headquarters.
During that interview, in which Holmes had plastic bags placed over his hands to preserve any traces of gunpowder residue, Holmes also gestured with one of the bags as if it were a talking hand puppet, the detective testified. (Reporting by Keith Coffman; Writing by Steve Gorman; Editing by Cynthia Johnston and Lisa Shumaker)