Among the dead were a 51-year-old father who had gone to the theater with his two teenage children. They escaped with no physical injuries.
Holmes has pleaded not guilty by reason of insanity and will undergo a mental evaluation at the state hospital before the trial.
Prosecutors are seeking the death penalty.
The trial is scheduled to begin Feb. 3, and since jurors will wield life-and-death power over Holmes, jury selection is likely to be slow, painstaking and contentious.
Once they are chosen, the jurors will be asked to weigh a staggering amount of evidence.
Prosecutors needed 2 1/2 days to present a rough outline of their case at a preliminary hearing in January, calling witnesses and showing photos and documents that pointed toward an intricately planned assault.
The case has generated nearly 40,000 pages of evidence, and more is on the way. This month, the judge granted prosecutors access to a notebook Holmes had sent a psychiatrist before the shootings. A receipt filed with the court shows the notebook was turned over to police on June 10.
Prosecutors have said that in addition to reviewing the contents of the notebook, they want police to do unspecified "additional processing" of it.
For its part, the defense has filed more than 130 motions to date, and the deadline for motions about the death penalty is still more than three months away.
Defense lawyers have said they plan to seek a change of venue because of pretrial publicity.