Can they get in trouble for blackmail or something else?

My friends stole 5 dollars from someone and they caught it on camera. The kid's parents brought it to his attention that they had it on camera and told him that if he got into any confrontation or says anything about their kids they were going to call the authorities and report the theft. It has now been about a month and they are still holding this over his head everyday at school. And on top of that they are making statuses and tweets about him but not mentioning his name but its very noticable who they are talking about because of the situation. They also threaten to expose him all the time. Can he get in trouble for the theft since its been so long and the fact that they are holding it against him and taking bad about him? My friend has not said anything so that they wont report the theft. What can he do?