I would be very suprised if the person who had it was not the thief.... otherwise why would they have given up the freewheel and I am assuming the brake(s) they put on it so easily? Though they may have sold the fixed hub and wheel for more than it cost them to buy the freewheel I suppose. (btw - unless they put shifters on it too, they just converted it from a fixie or fixed gear, to a single speed, which only has one gear, but is able to freewheel, for those who like the cool-factor of a single speed, but aren't so sure about the not being able to stop pedaling part if its a fixie- some people use what's called a flip flop hub that is fixed on one side and freewheel on the other - take off the wheel, turn it around and you've changed the bike - but you really should have two brakes on a single speed!)