Sounds like an extremely important issue (no facetiousness implied); have you considered just outright asking him?
I'm sure if you dressed it up as "investors requiring proof of service from anyone with service credentials involved in the project" etc then you'd get your answer. Any evasiveness would make me think he's full of it.
Every pilot will know where their logbook is if nothing else, and I don't know a single FJ mate without at least a handful of posed by-the-cockpit photos that are easy to access!