Courtroom sketch of James Holmes

(Sketch: Courtesy of Bill Robles)

The key events leading up to the Aurora theater shooting, and its aftermath.

May 2011 - Gunman James Holmes moves to Aurora and soon begins taking neuroscience classes at the University of Colorado Anschutz Medical Campus.

May 2012 - Holmes begins to buys guns at outdoor stores in Denver and Aurora.

June 7, 2012 - Holmes fails exams at CU Anschutz, which the prosecution links to the shooting.

June 7, 2012 - Holmes buys another firearm and more ammunition.

June 10, 2012 - Holmes withdraws from CU Anschutz. 

June 11, 2012 - CU psychiatrist contacts campus police with concerns about Holmes. 

June 29, 2012 - Holmes takes photographs inside the Century 16 in Aurora, the site of the shooting. 

July 5, 2012 - Holmes takes photographs outside of the theater. 

July 19, 2012 - Holmes takes self portraits hours before shooting, testimony from prosecution says. 

July 20, 2012 - Holmes opens fire at a midnight screening of The Dark Knight Rises at an Aurora movie theater, killing 12 and wounding 70. Holmes is arrested at the theater. President Obama decries the shooting as "senseless."

July 21, 2012 - Police disarm booby traps at Holmes' apartment. 

July 23, 2012 - Holmes makes his first court appearance 

July 24, 2012 - Firearm sales surge in the days following the shooting as people fear new gun control laws will be implemented. 

July 30, 2012 - Holmes faces 24 counts of murder and 116 counts of attempted murder as formal charges are filed. 

Sept. 28, 2012 - Documents show that University of Colorado officials banned Holmes from campus after he threatened a school psychiatrist. 

Jan. 17, 2013 - Theater reopens months after shooting. 

April 1, 2013 - Prosecutors say they will seek the death penalty, rebuffing a plea deal from Holmes. 

May 13, 2013 - Holmes enters not guilty by reason of insanity plea. 

Oct. 8, 2014 - An independent report gives Aurora's emergency responders high marks. The report concluded that the "outcome could not have been better in terms of lives saved and a rapid arrest."

Dec. 19, 2014 - Holmes' parents Robert and Arlene plead for their son's life. "We love our son, we have always loved him, and we do not want him to be executed," they wrote in a letter to the Denver Post. 

Jan. 19, 2015 - After months of delays, the trial begins with jury selection. The trial is expected to last 10 months.

Feb. 3, 2015 - Court costs for the Holmes case exceed $5 million, records show. 

April 27, 2015 - Opening arguments begin in court.