Thank you for trusting your question to JA today. I am a licensed attorney with over a decade of law practice and over 20 years of experience in the legal field. I’m happy to be of assistance.
Police officers fit into a specified exemption in the FSLA called the Section 7(k) exemption. That means that they only have to be paid overtime on a pay period basis and that pay period doesn't have to be 7 consecutive days. It can, instead, be a pay period of up to 28 days. This is permitted for the shift type work that police officers and firefighters have very often. So, if they are running him on a 28 day pay period, this "could" be legal. Additionally, the are allowed to pay for overtime with comp time under 7(k), something that is not permitted in the civilian world.
My point here is not that I think this is legal, but rather, that on the face of your facts I can't positively determine that it is illegal because there would have to be a fairly deep exploration of his hours in relation to the pay period and in relation to any comp time that is banked, etc. Certainly, if he is receiving no comp time and there isn't a significant period of time blocked in for him to be off in the near future, there is no way they could be meeting even the 28 day rule at which point he'd need to file a complaint with his state's Department of Labor (he could even do it anonymously) to have the matter investigated.
If you have any further questions, please let me know. I invite follow up questions, so use REPLY for those. If you have no further questions then good luck going forward and please do not forget to rate my service with a top-three rating so that I receive credit for working with you today. Also, feel free to request me in the future, if you have questions concerning a different matter.