"Facebook launched an initiative that gives users who have expressed suicidal thoughts the option to connect directly with a crisis counselor via Facebook chat. Facebook doesn't troll the site in search of those who might be suicidal; with 800 million users who generate billions of posts, Facebook's algorithm could easily misinterpret comments. Instead, the new initiative is dependent on people speaking up when they feel a friend might be in danger."
http://www.pcmag.com/article2/0,2817,2397551,00.asp