( CNN) The suicide of former NFL player Aaron Hernandez in his prison cell is one of several recent suicides of people in custody, inspiring experts to question whether these deaths were preventable.

Hernandez, who was convicted of slaying in 2015, hanged himself Wednesday morning with a bedsheet tied to his window, according to prison officials. A Washington country inmate accused of fatally shooting five people last year likewise hanged himself this week, and a triple-murder suspect lately fell from the fourth storey of an Ohio courthouse in an apparent suicide, according to police.

Hernandez was reportedly placed on suicide watch in 2015 after he was convicted for the assassination of Odin Lloyd, for which he was serving a life sentence without the opportunities offered by parole. But there has been no manifestation he was on suicide watch. An investigation into his death is ongoing.