If someone takes something by mistake and returns it the next day?

I have a friend who is caught up in a bad situaion He is a artist and took a camera from a club and put it in someone else's bag. Ideally he thought that it belonged to someone from the team. The club has CCTV footage of him taking the camera, and putting it in another person's bag. The another person then takes the camera and walks away. When the club manager asks for the camera, he realized that it was a mistake and the camera was returned to the club within a day. The club manager then called my friend, who had taken the camera and told him that he understands that it was a mistake and wants to clarify the same with the club owner. Then they said that the CCTV footage clearly states that it is not a mistake .The manager and the club owner do not let my friend go and say that he will need to pay a settlement fee of 5 Lakhs even though the camera is returned. Finally after pleading, they settle for 20000 rs and are blackmailing him even post that to complain to the police.