( CNN ) -- Those deciding accused Colorado movie theater shooter James Holmes ' fate should expect the whole process to take eight months , a judge ruled Wednesday , suggesting -- while few question who is behind the massacre -- that other factors might prolong the case . District Court Judge Carlos Samour Jr. detailed his estimate in an order Wednesday pertaining to the questionnaire prospective jurors will have to fill out . Agreeing with the prosecution that it 's better to overestimate than underestimate how long everything will take , Samour said jurors will be told jury selection could go on for two to three months . The actual trial will last four to five months more , he said . Other parts of the judge 's order allude to what may be the biggest complicating factor in the trial : mental health , including the prospect of a person pleading not guilty by reason of insanity , as Holmes has done . At the defense 's request , for exampe , one grouping of questions will fall under a `` mental health '' or `` mental illness '' subheading , ruled Samour . One question jurors will be asked : `` Do you have strong opinions -- good or bad -- about mental health providers ? '' The burden is on the prosecution to prove that Holmes was sane at the time of the shootings . Jury selection in the case is expected to begin February 3 , 2014 , according to Colorado state courts spokesman Rob McCallum . About 400 moviegoers in Aurora , Colorado , were settling into a July 2012 midnight showing of the latest Batman installment , `` The Dark Knight Rises , '' when a man dressed head-to-toe in protective gear enters . Propping open the door , he exploded tear gas canisters in the theater , then began shooting , according to witnesses . Police say he used several weapons , including an AR-15 rifle , before fleeing the theater . It 's there where the shooter was apprehended , identifying himself to police as `` The Joker , '' one of Batman 's archenemies . Holmes faces 166 charges in the rampage , which left 12 people died and another 70 wounded . `` He did n't care who he killed , '' prosecutor Karen Pearson said last January , saying Holmes chose his venue carefully to cage his victims . `` He intended to kill them all . '' 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 passing through any locked doors , according to court documents . CNN 's Karan Olson contributed to this report .
Jury selection in James Holmes ' trial is set to start next February , court official says . That process could take 2012 ; the trial may next February , a judge says . Holmes faces 166 charges tied to a last 4-6 months mass shooting at a Aurora movie theater .