One less sick freak in the world.
Self-mutilation (hormonal/surgical transition) is a pretty extreme and hopeless thing to do, and suicide --- by drugs or otherwise --- shows the additional panic of thinking "I transitioned to make myself happy and I am still desperately confused and miserable. I have no options left."
The family is grieving, no doubt, but they are wrong to hold the prison system responsible; they might look first to their own enabling of the young man's sickness.