CENTENNIAL, Colorado (CNN) -- A Colorado judge ruled Thursday that probable cause exists in the case of James Holmes, accused of killing 12 people and wounding Cscores more in last summer's shooting inside an Aurora movie theater, and ordered that he stand trial.
Arapahoe County District Judge William Blair Sylvester, who ordered that Holmes be held without bail, converted a status hearing scheduled for Friday to an arraignment.
In his 61-page ruling, Sylvester said the prosecution had established probable cause in all 166 counts, including first-degree murder.
A defense request for a continuance of the arraignment will be taken up Friday, a court administrator said.
The 25-year-old former doctoral student in neuroscience at the University of Colorado, Denver, faces 166 charges, including murder, attempted murder and weapons offenses, tied to the July 20 rampage during a screening of "Batman: The Dark Knight Rises."
Sylvester's decision came after a three-day hearing this week in which prosecutors presented evidence against Holmes.
"He didn't care who he killed," prosecutor Karen Pearson told the judge at the conclusion of her case against Holmes, saying he chose his venue carefully to cage his victims. "He intended to kill them all."
The shootings killed 12 and wounded 58.
Defense attorneys, who had been expected to call witnesses and argue a diminished capacity defense, changed their minds during the hearing, attorney Dan King said.
"We have had a change of position," he said. "This is neither the proper venue nor the time to put on a show or present some truncated defense."
After the hearing, some of the victims' relatives asserted that Holmes was too calculating to be afflicted with diminished capacity.
"He's not crazy one bit," Tom Teves told reporters Wednesday. His son Alex, 24, was among those killed.
"He's very, very cold. He's very, very calculated," Teves said of Holmes. "He has a brain set that no one here can understand, and we want to call him crazy because we want to make that feel better in our society.
"But we have to accept the fact there is evil people in our society that enjoy killing any type of living thing. That doesn't make him crazy," Teves said.
Added Jessica Watts, cousin of Jonathan Blunk, also killed in the theater: "It was complete planning. It was competency. It was everything on his part to make sure that this act was carried out from start to finish."
According to hearing testimony, here is what is known about his alleged preparations:
Holmes began buying guns in May, supervisory agent Steve Beggs of the Bureau of Alcohol, Tobacco, Firearms and Explosives testified on Tuesday. Beggs said Holmes built an arsenal of two Glock handguns, an AR-15 rifle, a shotgun and 6,295 rounds of ammunition.
Among other purchases, Beggs said Holmes bought two 6-ounce tear gas grenades over the Internet on May 10 and he went to a gun store on May 22 to buy one of his Glocks.
A little more than a month later, on July 1, a video camera captured Holmes as he bought a scope, a mount and some inert ammunition at a Colorado gun store, Beggs said.
In the video, Beggs said, Holmes' hair is dyed bright orange.
A police detective testified that Holmes apparently visited the cinema and took photographs of hallways and doors several times before the shootings.
The photographs were recovered from Holmes' cell phone and go along with months of sales records and descriptions of meticulously prepared booby traps at his home. It all helps illustrate what would appear to be a well-planned attack.
On July 7, Holmes used an online ticketing service to buy a ticket for the midnight showing of the movie, according to Detective Craig Appel, the lead investigator in the case.
Witnesses detailed preparations that prosecutors believe Holmes made before setting out for the theater to turn his sparsely decorated Aurora apartment into a deathtrap.
At least some of the preparations were well under way by July 16th, based on a photograph from Holmes' phone shown by prosecutors. In it, jars, wires, firework shells and other bomb-making materials are laid out in his kitchen.
By the time Holmes left, the carpet in his apartment had been soaked in oil and gas, FBI bomb technician Garrett Gumbinner testified. A container of glycerin hung above a frying pan with a potassium mixture, attached to a trip wire that would tip the glycerin into the pan, Gumbinner testified.
Had it been triggered, Gumbinner said, it would have set off an explosion and fire, igniting jars of homemade napalm spiked with bullets and thermite -- a metallic substance that burns so hot it is nearly impossible to extinguish.
In a twist that seems ripped from the pages of a comic book, Holmes also rigged his computer and a boom box placed outside to begin playing loud music after he set out for the theater -- apparently in hopes that the noise would prompt someone to investigate and trigger the explosives, witnesses said.