HI Buddy..
First, You must have their receipt.
And it's not enough if it wasen't in your name to sell them, unless the owner is along with them with valid Qatari I.D and if you don't have a receipt @ all then you need to verify & clarify them @ police station, for registration and quick investigation, just to assure the source of the gold beside if there's any case toward them .
then they will isue a note which's entitling you to sell them in the market or personally.