James Holmes trial: Why insanity defense is a long shot

James Holmes acknowledges killing 12 people and wounding 70 more inside a packed Colorado theater in 2012, but has pleaded not guilty by reason of insanity. His trial begins Monday.

The parents of Colorado theater shooter James Holmes joined the parents of his victims in line on a gray and drizzly Monday morning before entering the courthouse where lawyers prepared to declare why he should be executed or spend the rest of his life in a mental hospital.

The key to the fate of Holmes will be determining what was going on inside his mind as he slipped into a midnight Batman premiere, threw smoke canisters and then marched up and down the aisles, firing at anyone who tried to flee.

James Holmes acknowledges killing 12 people and wounding 70 more inside the packed theater, but has pleaded not guilty by reason of insanity. His parents, Robert and Arlene Holmes, have pleaded for their son's life to be spared, calling him a "human being gripped by a severe mental illness."

Unlike most other states, Colorado puts the burden on prosecutors in insanity cases: They must convince jurors beyond a reasonable doubt that Holmes was sane. It adds another obstacle for a state that has already spent millions to manage an outsized number of victims, hundreds of witnesses and more than 85,000 pages of evidence.

Even so, experts say Holmes faces long odds. Insanity defenses are successful in only 25 percent of felony trials nationally, even less so in homicides.

"Lay people tend to think of people with mental illness as extremely dangerous, and that also influences jurors, especially if someone has killed someone," said Christopher Slobogin, a professor of law and psychiatry at Vanderbilt Law School. "Usually there's evidence of intent and planning that seems to be counterintuitive to the lay view of mental illness."

Winning a trial on mental-health grounds is rare, but then again, so is a jury trial for a mass shooter, many of whom are killed by police, kill themselves or plead guilty.

A review of 160 mass shootings found killers went to trial 74 times, and just three were found insane, according to Grant Duwe, a Minnesota corrections official who wrote the book "Mass Murder in the United States: A History."

Just one mass shooter has won a mental-health case in the last two decades, Duwe said: Michael Hayes, who shot nine people, killing four, in North Carolina in 1988.

Based on that, Holmes "faces some pretty long odds," he said.

Holmes was arrested almost immediately, while stripping off his body armor in the parking lot outside the Century 16 movie theater. That he was the shooter who replaced Hollywood violence with real human carnage has never been in doubt. The victims include a 6-year-old girl, two active-duty servicemen, a single mom and an aspiring broadcaster who had survived a mall shooting in Toronto. Several died shielding friends or loved ones.

Nearly three years have passed as trial preparations were stalled by complicated legal debates over capital punishment and insanity pleas.

Prosecutors will argue that the once-promising doctoral candidate in neuroscience plotted and planned for months, amassing guns, ammunition, tear gas grenades and enough chemicals to turn his dingy apartment into a potentially lethal booby trap that could have caused even more carnage.

They'll ask jurors to find him guilty, and if so, sentence him to death rather than life without parole.

If jurors decide instead that Holmes was insane at the time of the shooting, he would be committed indefinitely to a state psychiatric hospital.

Dueling mental health evaluations could factor in their deliberations. Judge Carlos A. Samour Jr. ordered a second exam after prosecutors said the first was biased. Defense attorneys have objected to the results of the second one, suggesting it might not help them.

Like many other details, the results of both exams have been kept from public view. Also secret is the list of people expected to testify.

Holmes faces 166 counts, including first-degree murder, attempted murder and an explosives offense.

The judge read each charge, naming each victim, out loud. It took nearly two hours.

Holmes' trial could take at least four months or more and is sure to be emotionally wrenching. Jury selection alone took nearly three months as attorneys and the judge settled on 12 jurors and 12 alternates from a pool of 9,000. Experts said the jury selection was among the largest and most complex in history, in part because it was so difficult to find people who weren't personally affected by the shooting.

Holmes' parents begged prosecutors to consider a plea deal sparing his life and avoiding a drawn-out trial. But some survivors want Holmes executed, even if that means reliving horrific details.

"It still doesn't bring him back, but we want justice," said W. David Hoover, who wants to avenge the death of his 18-year-old nephew, A.J. Boik. "Real justice is going to happen when this animal leaves this Earth."

Fire Chief Larry Trujillo, whose daughter, Taylor, survived the shooting when a friend threw her to the floor, said Monday before entering the courthouse that his faith enables him to forgive, but that this may be easier for him to say because his daughter survived.

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