The Ohio teenager accused of strangling his ex-girlfriend on a senior trip to Myrtle Beach, South Carolina, allegedly locked himself in a room with her corpse for hours, then emerged after stabbing himself in the chest, according to the victim’s best friend.

Police say Blake Linkous fatally choked Natalie Martin, both 18, inside a vacation rental on Maison Drive on June 6, where at least five other friends were staying for the post-graduation celebration-turned-nightmare.