A police officer on the late shift in an Ohio town recently received an unusual call from Facebook.

Earlier that day, a local 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 who took the call 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 work-up, an evaluation prompted by Facebook’s intervention. (The New York Times withheld some details of the case for privacy reasons.)

Police stations from Massachusetts to Mumbai have received similar alerts from Facebook over the last 18 months as part of what is most likely the world’s largest suicide threat screening and alert program. The social network ramped up the effort after several people live-streamed their suicides on Facebook Live in early 2017. It now utilizes both algorithms and user reports to flag possible suicide threats.

Facebook’s rise as a global arbiter of mental distress puts the social network in a tricky position at a time when it is under investigation for privacy lapses by regulators in the United States, Canada and the European Union — as well as facing heightened scrutiny for failing to respond quickly to election interference and ethnic hatred campaigns on its site. Even as Facebook’s chief executive, Mark Zuckerberg, has apologized for improper harvesting of user data, the company grappled last month with fresh revelations about special data-sharing deals with tech companies.