She can insist on filing a report; most departments you can file a report whether or not the police want to do anything about the case. Filing a report does not mean that they are going to do anything. I do not seem how there is a cause of action against the Police [claims must be filed within 6 months of the incident]. Even if she did, what are the damages from the police not acting? She should have canceled the checking account upon first finding out about the thief. She should tell the person who took the checks she knows they did it and immediately sue them in Small Claims Court. A judgment might cause the police to act. She needs to go to the District Attorney's Office to see what can be done, if she can not go to a higher level in the police department to get them to act.