This might be what you were thinking of
Florida mental health agency examined Cruz in 2016, didn’t hospitalize him
"Crisis workers from a South Florida mental health facility were called in 2016 to hold alleged gunman Nikolas Cruz for a psychiatric evaluation after he sent out a Snapchat video in which he cut his arms and said he wanted to buy a gun, according to a mental health report.
But after speaking with Cruz, Henderson Behavioral Health health professionals chose not to hospitalize him, according to a November 2016 Florida Department of Children and Families investigative report obtained by NBC News."
http://wfla.com/2018/02/19/florida-mental-health-agency-examined-cruz-in-2016-didnt-hospitalize-him/