Who can you call to confront a medically retired veteran who is collecting a check and doing illegal drugs?

Marijuana is borderline reportable anymore in the silly villain world and if they are medically retired self medicating is not an unknown thing. I'm not in your shoes and I don't know who you are or what expertise you have or what these people have done to give you that impression. As it is more than one that you have seen ((if I am reading this right)) I would suggest waiting a moment before acting and perhaps finding some guidance in your leadership to offer you some advice.

But if you have to act, I would suggest the inspector general, but if you do feel as if you must act, I would suggest leaving your contact info when you file the complaint. If nothing else you owe it to them to give them the option to look you in the eyes.

Do you have any knowledge of the actual facts about their medical conditions or did you just self diagnose them from a distance? While it's possible they fooled everybody, there was at one point a chain of command and doctors involved in determining they should be medically retired. So I would be very reluctant to accuse someone of faking. It's sort of like the way I'm against soldiers challenging vets about stolen valor. Senator John McCain gets 100% disability payments from his time in service. But you can't necessarily see all that's wrong with him by observing him on TV. And why do you seem to be so concerned about the "wrong" things they do? If they weren't doing marijuana, and were straight arrows, would you still feel like reporting them about their retirement checks?

If you think they are defrauding the government in order to collect a medical retirement, I think an IG call would probably be the best bet. People do regularly abuse things like Workman's Comp, so I wouldn't put a fraudulent medical retirement outside the realm of possibility.

If the only issue is their personal choice of medication, I'm not sure if it's worth the bother to do anything about it. They are entitled to VA care regardless of usage. If permanently medically retired, there's a lot of aggravation on the military's part (form my understanding). Someone would need to be reactivated to face court martial. If all you've got evidence-wise is a witness account of someone smoking pot, I don't imagine the JAG to be super keen on going through that whole process. Simple possession is a summary offense is many jurisdictions, the same level of crime as a rolling stop at a stop sign. If someone got caught with a few pounds on them, maybe it'd be a different story.

So you could try local law enforcement, but unless you live in the quietest of towns, most cops don't really care about simple possession (my dad is a retired cop, and I have friends and family that are LEOs). A call likely would not provide probable cause, leaving the cops to knock on the door, get told that the person inside isn't getting high, and that's the end of the discussion if there isn't a state marijuana law. There are usually crimes that require less effort and/or have a bigger public safety impact that they'd rather deal with.

All in all, there's not a ton that can be done.