A police officer on the late shift in an Ohio town recently received an unusual call from Facebook. That day, a woman wrote a Facebook post saying she was walking home and intended to kill herself when she got there, according to a police report on the case. Facebook called to warn the Police Department about the suicide threat. The officer quickly located the woman, but she denied having suicidal thoughts, the police report said. Even so, the officer believed she might harm herself and told the woman that she must go to a hospital — either voluntarily or in police custody. He ultimately drove her to a hospital for a mental health checkup, an evaluation prompted by Facebook’s intervention.