Theft is a both a crime--so you could report them to the police--and a civil tort--or something which you could sue about. One thing which might stymie you, at least in part, is what is known as the "statute of limitations," or time to sue. For an intentional tort--i.e. an intentional bad act, like theft--it's often short; it may be as short as 1 year. That would mean that you could only sue for losses within the past year, though there are some doctrines or rules that may let you extend the time to sue (sometimes, if it would have been very difficult to discover the tort initially, the plaintiff's time to sue is extended to when he or she did discover it, or at least to when he or she had a reasonable opportunity to discover it).Reporting to the police may get you justice, but it probably won't get you compensation. Suing is how you would get money back. If you think you have a case (e.g. evidence), you should contract an attorney immediately, before more time goes by.