16 months ago citizen finds a FN Herstal 5.7 handgun (a very expensive handgun, apparently) with one round missing from magazine. Turns it over to police. Gun not reported stolen. Name and address of last known owner found through ATF, but owner has since moved and no response when contacted by PD. No match for weapon in any crimes reported in metro area. Citizen who found gun now wants it back, so he can sell it. Now what?

I don't think CCP 18.17 applies, as this doesn't sound like property seized by a peace officer. I perused the Property Code. Ch. 72.101 says three years must pass for property to be presumed abandonded.

Any help will be appreciated. I will also post in the civil section.