This guy thinks he is an expert investigator. he is a total fake.
Caller is extremely aggressive and agitated. Calls to "investigate" and seems to think he is some kind of police investigator. Clearly mentally unwell. Seems una@$#%!e to maintain a coherent train of thought when he gets excited, and begins slurring his words. Gets excited a lot, particularly when you challenge his delusional world view.
May not be a scam, but best to just hang up on this guy, as nothing good can come from feeding his delusions.