CENTENNIAL, United States: The American gunman who stormed a Batman movie premiere and killed 12 cinemagoers escaped the death penalty Friday but will spend the rest of his life behind bars. A Colorado jury failed to unanimously agree on execution for 27-year-old former graduate student James Holmes, obliging the judge to impose a sentence of life without parole. Last month, the killer had been convicted on 12 counts of murder in the first degree and scores more charges including murder, attempted murder and explosives possession. But defense counsel argued he has a mental illness and urged jurors to show clemency, an appeal apparently heeded by at least one of the panel of nine women and three men. On each of the 12 murder counts that could have merited the death penalty, the jury said in a statement read to the court: “We do not have a unanimous final sentencing verdict on this count.” Holmes attacked the packed premiere of “The Dark Knight Rises” at the Century 16 theater in Aurora on July 20, 2012, spraying bullets into the dark auditorium.