Family said Colorado suspect had 'mental illness.' Experts say that's rarely the cause of mass shootings.

After 10 people at a Colorado supermarket were gunned down this week, a question familiar in America's cycle of bloodshed began to echo: Does mental illness drive mass shootings?

The 21-year-old suspect arrested in the rampage, the second in a week, was almost immediately described by family members as paranoid and antisocial.

But researchers and advocates say the rush to cast blame on a mental illness is misplaced.

"There's no psychotic illness whose symptom is shooting other people," said Dr. Jonathan Metzl, director of the Center for Medicine, Health...