Someone stole a check from me and received my money. The check was from a large company, and they don't seem helpful in assisting me in resolving the issue. I don't know who stole the check.

1. Is there a way to figure out who cashed the check without the assistance of the company which issued the check? Can the police do this easily?
2. Is the company under any obligation to assist me with this problem?
3. Am I right in assuming that the company which issued the check can easily call their bank and figure out who deposited it? Will this work even if the check was cashed instead of deposited?