Key dates in the life of James Holmes, on trial in the 2012 Colorado theater shooting:

Dec. 13, 1987 — Holmes is born in San Diego County, California, to Robert and Arlene Holmes.

2006 — Graduates from Westview High School in San Diego.

2010 — Graduates from the University of California, Riverside, with a B.S. in neuroscience.

2011 — Holmes enrolls in the Ph.D. neuroscience program at the University of Colorado's Anschutz Medical Campus in the Denver suburb of Aurora.

May 10, 2012 — Orders tear gas canisters online, according to prosecutors. Over the next few weeks, he also buys two handguns, a shotgun, an assault rifle, 6,295 rounds of ammunition and body armor, either in person or online, prosecutors say.

June 10, 2012 — Files paperwork to withdraw from the neuroscience program but doesn't say why.

June 11, 2012 — Meets with his psychiatrist, Lynne Fenton of the University of Colorado. Fenton tells a campus police officer Holmes has made homicidal statements and sent her threatening text messages.

July 20, 2012 — Holmes slips through a back door of the Century 16 theater in Aurora, where about 420 people are watching a midnight showing of a Batman movie, "The Dark Knight Rises," and opens fire. Ten people die at the scene, two die at hospitals, and 70 are injured. Officers find Holmes leaning against his car behind the theater and arrest him without a struggle. Later, police find booby-trapped bombs and a Batman mask at Holmes' apartment. The bombs are defused.

July 23, 2012 — Holmes makes his first court appearance, his hair dyed orange-red, face unshaven, eyes appearing dazed.

Oct. 11, 2012 — Prosecutors finalize the charges against Holmes: 24 counts of murder and 140 counts of attempted murder, two counts for each person killed and two for each person injured. He's also charged with possession of explosives and committing a crime of violence.

Nov. 15, 2012 — Holmes is taken to a hospital psychiatric ward and held for several days, sometimes in restraints, because he was "in immediate need of a psychiatric evaluation," according to his attorneys.

Jan. 10, 2013 — The judge rules the evidence is sufficient to put Holmes on trial.

March 27, 2013 — Holmes' attorneys say he's willing to plead guilty in exchange for avoiding the death penalty. Prosecutors later reject the plea offer, saying it isn't genuine and that Holmes is sane.

April 1, 2013 — Prosecutors say they'll seek the death penalty.

May 13, 2013 — Defense lawyers tell the judge Holmes wants to plead not guilty by reason of insanity.

June 4, 2013 — The judge accepts Holmes' insanity plea and orders Holmes to undergo a mental evaluation.

July 10, 2013 — Holmes' lawyers acknowledge he was the shooter but say he was "in the throes of a psychotic episode."

Nov. 7, 2014 — The judge says he'll issue 9,000 jury summonses, believed to be the largest number ever for a U.S. trial.

Jan. 20, 2015 — Jury selection begins.

April 14, 2015 — Twelve jurors and 12 alternates are chosen to hear the case.

April 27, 2015 — Prosecutors and defense lawyers are scheduled to make their opening statements.