A poster here who lives in Texas I believe said there was a recent incident in her town in which a young man who had converted to Christianity from Islam was shot to death in a public place by his cousin as punishment.
Fortunately, it's not often carried out in the US, although I know several ex-muslims who have had death threats for their change of religion. I also know an agnostic who apparently receives regular death threats as well for her leaving Islam.
Hopefully, the cousin is another addition to Texas's death row.