Do you have a source for that roommate story? I'm going to assume the story was either figured out by law enforcement after they investigated the corpse, or it was shared anonymously by someone who knew of the pair's plan, as I doubt the shooter himself would be sharing the story unless he wanted to incriminate himself. I feel like, to avoid the legal consequences of such a manner, a better (but more convoluted) solution to complete this plan would be for the individual to build some sort of timed contraption that fires during their own slumber.
It may sound comical, but my immediate thought of what this contraption could be is where the individual would tape the firearm to their bed's headboard with the barrel facing down to their face, run a strong string/wire around the trigger that loops around the gun and droops down to a bedside table, tie the loose side of the string to a strong weight, set the weight on the edge of the table, and then set a harshly-vibrating alarm clock's timer for four hours (turning off its audio so that it doesn't wake the individual) so that, when they fall asleep, after a few hours of rest, the alarm will vibrate, the weight will drop, and the trigger will be pulled by the string's resulting tension, firing the gun (for extra security if the person moves a lot in their sleep, they might want to find a way to suspend their arms and legs as their last step in order to ensure that they don't move out of the barrel's way). I don't know if that plan would actually work, as I may just have an active imagination, but I've attached a diagram to explain it visually. It would still allow the individual to perish from a gunshot in their sleep without making another person liable.
