I've heard similar stories.

In one instance, the local crossed the wrong woman. After she left, her brothers came to Qatar on tourist visas. They found the man and proceeded to torture him for two days (leaving him alive). They then returned home casually, and when they landed they phoned a friend/relative of his to tell where he could be found.

Few countries (and no Western ones) extradite to Qatar, so there is little that could be done in return.