James Holmes appears in court, Centennial, Colo., July 23, 2012. RJ Sangosti/AP Images.

ABC's Clayton Sandell and Carol McKinley report:

A judge ruled Thursday that public defenders for accused Colorado theater shooting suspect James Holmes can call two unidentified witnesses at next week's preliminary hearing to testify about the defendant's "mental state."

Arapahoe County, Colo. prosecutors had sought to keep the witnesses out of court, but Judge William Sylvester ruled that the now-25-year-old accused killer has a right to call the witnesses at a preliminary hearing.

The Jan. 7 preliminary hearing will essentially be a mini-trial in which prosecutors will present witness testimony and evidence to convince the judge that there is enough of a case against Holmes to proceed to a trial.

Witnesses to be called for the prosecution include the Aurora police lead detective, first responders, the Arapahoe County coroner and likely a computer forensic specialist, according to prosecution sources who declined to be identified, citing a gag order in the case.

A top priority, the prosecution sources say, will be showing that Holmes acted with premeditation when he allegedly murdered 12 people and wounded 58 on the night of July 20 during a midnight showing of "The Dark Knight Rises."

Defense attorneys may pursue a legal strategy to show that Holmes was not in his right mind at the time of the shooting.

Holmes, who has not yet entered a plea, has been repeatedly described in court by his legal team as mentally ill. While a graduate student at the University of Colorado, he was in the care of a psychiatrist.

Prosecutors say they will also present photos, video and 911 calls during the hearing, which is expected to last all week.

It's not clear what the two witnesses' relationship is to the shooting, or to Holmes.

Prosecutors, Judge Sylvester's order says, contend that "neither witness has personal knowledge of the events at the Century Aurora 16 Theater."

Sylvester said the witnesses are non-expert "lay witnesses" who have so far chosen not to be interviewed by defense investigators but have been cooperating with law enforcement.