AURORA | With just three weeks before jury selection begins in the Aurora theater shooting trial, the two sides are sparring over testimony from expert witnesses.

In a motion unsealed Wednesday, prosecutors asked Judge Carlos Samour, Jr. to compel the defense to turn over notes from psychiatrists they may call as witnesses. According to the motion, the witnesses could be called during the death penalty sentencing phase of James Holmes’ trial, assuming a jury convicts the accused shooter at trial.

Prosecutors said that without the notes they won’t have any idea what the defense experts could say in front of the jury.

“This would turn the sentencing phase of the trial, at least as far as defense expert witnesses are concerned, into trial by ambush,” prosecutors wrote.

The defense has yet to respond to the motion. Samour gave the defense until Friday to respond.

Holmes is accused of killing 12 and wounding dozens more during a July 2012 attack at an Aurora movie theater. The trial, which is set for jury selection in January and opening statements in May or June, is expected to hinge on whether Holmes was sane at the time of the killings.

His defense has admitted that Holmes was the gunman, but said the former neuroscience student he was in the midst of a psychotic episode at the time.