Article from the Nashville Tennessean about a psychologist who investigates:

Mario Martinez follows the trail of blood to one of the biggest mysteries in religion — the human capacity to produce stigmata, the "wounds of Christ" on the hands, feet and forehead.

Martinez is a Nashville-based clinical psychologist who has traveled the world investigating stigmata claims. He was featured last week on the National Geographic Channel examining the crucifix-like wounds of a 53-year-old Catholic woman in Mexico City.

On the program "Is it Real? Stigmata," the bloody shape of a cross is visible on her forehead. Martinez’s interrogation convinces him it’s not fraud, self-mutilation or hysteria, the usual explanations. Blood samples confirm it’s hers. He’s impressed by her spirituality and humility.

"As a scientist, I rule out possibilities," he says. "But I stay open. If I come in and say I believe this or refuse to believe that, I introduce a bias."