(CNN) -- A judge has ordered that accused Colorado movie theater shooter James Holmes undergo an additional sanity examination, saying there was good cause to believe previous testing was "incomplete and inadequate," according to a ruling issued Wednesday.

Arapahoe County District Judge Carlos Samour Jr. ordered Holmes to undergo an independent exam by the Colorado Mental Health Institute in Pueblo by early March, and the report must be filed by July 14.

Samour further ruled the new examiner may not take into account any mitigating factors that are identified in the state's death penalty statutes.

Prosecutors are seeking the death penalty against Holmes, who is accused of opening fire in a packed movie theater in Aurora, Colorado, during a July 2012 midnight showing of the latest Batman installment, "The Dark Knight Rises."

Authorities have said Holmes was dressed head to toe in protective gear.

Holmes allegedly threw tear-gas canisters in the theater and then opened fire on the patrons, according to witnesses. Police say he used several weapons, including an AR-15 rifle, before fleeing the theater.

Outside the theater, the shooter was apprehended, identifying himself to police as "The Joker," one of Batman's archenemies.

Holmes faces 166 charges in the rampage that left 12 people dead and dozens more wounded.

Holmes was a neuroscience doctoral student at the University of Colorado's Anschutz Medical Campus until the month before the attack; prosecutors have argued that he began plotting his attack while still enrolled.

The defense, meanwhile, appears to be focused not so much on what Holmes allegedly did that night but his mental state then and earlier.

A psychiatrist who treated him had warned campus police at the University of Colorado how dangerous he was, prompting them to deactivate his college ID to prevent him from passing through any locked doors, according to court documents.

Source: CNN, Feb. 19, 2014