For James Holmes, “justice is death,” prosecutors said Monday in announcing they will seek his execution if he is convicted in the Colorado movie theater attack that killed 12 people.

The decision — disclosed in court just days after prosecutors publicly rejected Holmes’ offer to plead guilty if they took the death penalty off the table — elevated the already sensational case to a new level and could cause it to drag on for years.

“It’s my determination and my intention that in this case, for James Eagan Holmes, justice is death,” District Attorney George Brauchler said, adding that he had discussed the case with 60 people who lost relatives in the July 20 shooting rampage by a gunman in a gas mask and body armor during a midnight showing of the latest Batman movie.

There was no audible reaction from the 25-year-old former neuroscience graduate student, who sat with his back to reporters, or from victims’ families in the courtroom. Holmes’ parents sat side by side in the gallery, clutching hands with fingers intertwined.

The decision had been widely predicted by legal analysts.

Within minutes of it becoming official, the trial was pushed back from August to next February, and Judge William B. Sylvester removed himself from the case, saying that now that the charges carry the death penalty they will take years to resolve and he does not have the time to devote to such a drawn-out matter.

Despite the potential for more delays, some of those who lost loved ones were happy with the prosecutors’ decision.

“I had a huge adrenaline rush,” said Bryan Beard, whose best friend Alex Sullivan was killed in the attack. “I love the choice. I love it, I love it.” He added: “I hope I’m in the room when he dies.”

But the prospect of a longer legal battle troubled others, such as Pierce O’Farrill, who was shot three times.

“It could be 10 or 15 years before he’s executed. I would be in my 40s and I’m planning to have a family, and the thought of having to look back and reliving everything at that point in my life, it would be difficult,” he said.

Legal observers said Holmes’ lawyers publicly offered a guilty plea in what may have been a bid to gain support among victims’ families for a deal that would spare them a painful trial and lengthy appeals.

The prosecution and the defense could still reach a deal before the case goes to trial.

Holmes’ lawyers have indicated in court papers they may instead pursue a defense of not guilty by reason of insanity. But that carries great risk: Prosecutors could argue that Holmes methodically planned his attack, casing the theater, stockpiling weapons and booby-trapping his apartment with explosives.

The judge newly assigned to the case, Carlos Samour Jr., warned defense lawyers that if they want to change Holmes’ plea, the longer they wait the harder it will be to persuade him to accept it.

If Holmes is found not guilty by reason of insanity, he will be sent to the state mental hospital, then returned to prison after treatment.

The massacre helped lead to last month’s passage of new gun control measures in Colorado, including a ban on the sort of high-capacity magazines that Holmes allegedly used to spray the theater with dozens of bullets in a matter of seconds. Seventy people were injured in the attack.