The Russians probably killed him. Wouldn’t want the real story of Iraq’s transfer of WMDs to Syria by Russia to get out. Remember how back then the dem politicians were going to Syria all the time and being photographed with Bashad etc. ?? There were pictures of Kerry and Pelosi kissing his backside. The Plot thickens.
I'm not normally a fan of conspiracy theories, but you might have something there.
Alternatively, the Russians spirited him (them) away to exile and never to be heard from again. The gift of life is the price for anonymity.