The time to do something was when you were onboard the ship. Since it was their employee who stole your laptop you should have gotten documentation of the whole investigation..names of Princess Staff and the name of the employee who stole your computer. At that point you should have told Senior Staff that you now hold them liable since they are the acting agent who discovered that their employee was responsible for stealing items from your stateroom. Whoever that person was you could have sued them in civil court and had the police at the port to make a formal arrest when you arrived at your home port. Trust me on this...Princess would have negotiated with you on this because they do not want things like this taking place where consumers can see or talk about. These are things we don't think of but nowdays you have to be prepared to do what is necessary to protect your rights.
There are other ways to get what you want but it's at the time you were the victim,,,not when you leave the ship and then want recourse. It takes a level head and negotiating skills to walk into their turf and get results.