Leonardo DiCaprio's stepbrother is reportedly missing.

'The Wolf of Wall Street' actor is reportedly distraught as his sibling, Adam Farrar, has been missing for a month since being released from a three-week stint in prison for theft and breaking the rules of his probation from previous arrests.

A family friend told The Sun newspaper: "Adam was in jail and now I don't know where he is. He was here at my house for about two or three days, then he just disappeared. I've tried calling him but his number is disconnected. I spoke to his dad a couple of days ago and still no one has heard from him.

"I've known him since kindergarten and I'm worried. He's gone off the rails in the past few years. He doesn't have a permanent home and he flits around from friends' houses and lord knows where else."

The troubled actor - who had a few film and TV roles as a child and is thought to have inspired Leonardo, 39, to pursue his own career - is the son of 'The Great Gatsby' star's stepmother Peggy, who married his father, George, when he was just one.

Adam, 42, has had a string of run-ins with the law and in 2000 he was arrested on suspicion of attempted murder when a girlfriend called the police and claimed he had choked her at their home. The case was later dropped.

The insider added: "Leo has tried to stick by him but their relationship has become more difficult in recent years. We are all worried about Adam."