Joe Schmoe was six years old when he killed his best friend; it wasn't his fault, it was just the way that he was made...
Joe was born with an auto-telepathic telekinetic feedback ability - he has the ability to unconsciously kill anyone who has thoughts of killing him. It doesn't matter if those thoughts are intended to be carried out - "it's the thought that counts" (to re-use a phrase). If someone has an idle though that the world would be better off without Joe being alive, then they die.
As a young adult, Joe is eventually incarcerated in prison, in solitary confinement. But he's still killing - everyone who benevolently wishes to end his solitary suffering, the relatives of those that he's inadvertently taken from their families.
How can we end this cycle of pain and suffering?
EDIT: Burki raised the question of suicide. While this might be an elegant idea, it bypasses other creative ideas. For the sake of the story, let's say that this ability is borne of self-preservation and suicide is not an option here (sorry).
Interesting discussion overnight and some clarification has been asked for.
In essence, Joe's defence is this: If someone wishes him dead, then they die. Thinking of Joe, or being afraid of him isn't necessarily fatal.
Let's put it another way. Consider any mass-murderer/psychopath/dictator and how many people would wish them dead.
Or another way. A cute girl/guy sells you coffee this morning - if you subsequently have a sexual fantasy about him/her, you die. If you're happy with just getting your coffee with a kind word, you're pretty safe.
It's also worth considering the new title of this question and spinning it around - who is the thought-crime killer - Joe, or the people who wish him dead?
Nevertheless, Joe is in solitary confinement - whether he got there by turning himself in, or was dragged in is open for interpretation. I'm not saying either happened, I'm just providing a framework for your imagination.