James Holmes, accused of the Colorado cinema massacre, could be given "truth serum" to help determine whether he is insane, Judge William Sylvester has ruled.
Holmes is accused of killing 12 people and injuring 70 others during a shooting rampage at a 'The Dark Night Rises' movie premiere. He is expected to enter a plea soon.
According to Sky.com, defense lawyers have indicated that Holmes might plead not guilty by reason of insanity.
If Holmes does plead insanity, Judge Sylvester has ruled that Holmes may have to submit to a "narco analytic interview" as part of the evaluation of his mental state.
A narcoanalytic interview is one during which patients are given drugs to lower their inhibition. Judge Sylvester also said Holmes could be given a lie detector test.
Last week, Judge Sylvester rejected defense claims that the court rules relating to an insanity plea were unconstitutional.
The court also heard evidence that Holmes spent months planning the mass killing, purchasing weapons, ammunition and body armor and booby-trapping his apartment.
"Was he suffering from a mental disease or defect that rendered him incapable of distinguishing right and wrong?" asked Craig Silverman, a former deputy district attorney. "If the defense had to prove that, that would be one thing. But here in Colorado the prosecution has to disprove it. To prove sanity beyond a reasonable doubt with James Holmes could be tough."