The district attorney who prosecuted Colorado theater shooter James Holmes says a jury's refusal to give him the death penalty doesn't mean the public is growing wary of capital punishment.

George Brauchler says Holmes will be sentenced to life in prison because a single juror blocked his execution. The remaining 11 jurors felt strongly that Holmes should die for the July 2012 shooting that claimed 12 lives and left 70 injured.

Brauchler says other jurors were surprised to learn that the holdout felt strongly in favor of a life sentence. Brauchler said testimony about his mental illness likely swayed the juror to show mercy.

The jury's indecision means Holmes will automatically be sentenced to life without parole, after an emotional, three-month trial that offered a rare look into the mind of a mass killer.