District Judge William Sylvester ruled Thursday night that prosecutors had presented sufficient evidence to proceed with charges alleging James Holmes killed 12 people and injured 70 others at a suburban Denver movie theater July 20.

Holmes is charged with multiple counts of first-degree murder and attempted murder.

The next major step is for Holmes to enter a plea during an arraignment hearing. Sylvester scheduled the arraignment for Friday but noted that defense lawyers will likely ask for a delay.

His defense attorneys filed papers earlier Thursday saying he’s not ready to enter a plea.

Holmes’ attorneys also objected to news media requests to bring cameras into the courtroom during the arraignment. Cameras have been barred from court since Holmes’ initial appearance in July.

If Holmes, 25, is convicted of first-degree murder, he could face the death penalty. Prosecutors have not said whether they would pursue that sentence.

At a preliminary hearing this week, prosecution witnesses testified that Holmes spent weeks amassing an arsenal and planning the attack at a midnight showing of “The Dark Knight Rises.” They also detailed an elaborate setup at Holmes’ apartment designed to explode at the same time as the theater attack several miles away.

Prosecution witnesses testified that Holmes began acquiring weapons in early May and by July 6 had two semi-automatic pistols, a shotgun, a semi-automatic rifle, 6,200 rounds of ammunition and high-capacity magazines that allow a shooter to fire more rounds without stopping to reload.

Holmes’ lawyers called no witnesses this week. They have said he is mentally ill.

The defense motion suggested the possibility of more delays in the case.

One possible reason that Holmes’ attorneys could ask for a delay is to seek a mental health evaluation by a doctor of their choosing. If Holmes enters an insanity plea, an evaluation would be done by doctors at the state mental hospital.

Either side also could argue that Holmes is not mentally capable of assisting in his own defense. If that happens, the judge would order a mental competency evaluation. Sylvester also can order an evaluation if he has his own questions about Holmes’ competence. Doctors at the state mental hospital in Pueblo would conduct such an examination, which can take months.

If Holmes were to be found incompetent, the case would come to a halt while he receives psychiatric treatment at the state mental hospital. He would remain there until doctors can restore him to competency, at which point the case would continue.

Once the judge rules Holmes is competent — either immediately after a competency hearing or after psychiatric treatment — and any other delays are resolved, Holmes would then enter a plea.

This happened with Jared Loughner in the Tucson, Ariz., shooting that killed six people and wounded 13, including then-Rep. Gabrielle Giffords. A federal judge ruled Loughner was incompetent to stand trial. After more than a year in treatment, Loughner was ruled competent, the case proceeded, and he entered guilty pleas. He is serving life in prison.

Ultimately, Holmes was widely expected to plead either not guilty or — more likely — not guilty by reason of insanity. In the latter case, too, Sylvester would order a psychiatric evaluation by doctors at the state hospital in Pueblo. A jury would consider that evaluation, along with testimony by expert witnesses, any other court-ordered evaluations and other evidence, in deciding at a trial whether Holmes is or is not guilty by reason of insanity.

If found not guilty by reason of insanity, Holmes would be committed to the state mental hospital for treatment. His case would be reviewed every six months. He conceivably could be released if he ever is deemed no longer insane.

“Insanity is what this case is going to turn on,” said Denver criminal defense attorney Dan Recht. “This is not a whodunit case.”

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Associated Press writer P. Solomon Banda contributed to this report.