Genarally yes he can be re-introduced back into the wild. If he's caught from the wild he CAN go back. How long has your friend had him & where is the too from? We have too's in Australia that people adopt temperarily & they are safely put back into the wild. Generally if your too came from the wild he will lose very little of his wildness & does survive. Your friend shouldn't have the too unless it was ill or unable to survive in the wild.