In 2001, there was a trial for theft. According to the court decision, the criminal ...?

...received a prison term and had to pay monetary compensation. He served his term, was released, but did not pay the money. Since we have very reasonable executive services, I intend to submit a statement with a demand to find out why the funds were not collected in my favor, who is to blame for this and why it was not entered in the register of debtors? In case of death of that person, is it possible to collect funds (children, other heirs, if any)? I have already submitted an application to the court office to receive a copy of the decision. How to act correctly?