Is there a way to verify a person’s service when you suspect them to be a fraud?

I have a guy in my neighborhood claiming to be a disabled veteran. He used to claim that he was combat injured in an incident on the Korean DMZ in 1988. I’ve backed him off of that but he’s still claiming to be a disabled vet. He says that he’s a member of every veterans service organization on the planet, including the VFW. I’ve not been able to verify any of that yet, but have a resource to reach out to. Any help with being able to verify this guy’s service or lack there of would be appreciated. I have his name and DOB, and the units that he says he served with.