So u rang police first , then asked to view bike ? did u take photos whilst u was there, viewing the bike ? and then ring the police straight after the viewing and compared picture ?
Here's the whole story.
I went to the police station with pictures of the bike, those of the advert and pictures of the default model. Luckily I had extensively modified the bike and most of my parts were still on there.
One of the officers was a bike nut, and he agreed with me that this must be my bike.
Then I called the seller, made an appointment for the next morning and went there with a police officer who pretended to be my father (the benefit of being 19 and rather small is that you can pose as a teenager).
He checked the bike out like a normal buyer would (feel the brakes, check the headset for play, and then turned it upside-down and checked the frame number.
As soon as he verified that it was indeed the number I reported stolen, he identified himself as a police officer.
Of course the seller didn't see that coming. Luckily for him, he had made a sort of "purchase form" (with his name, the name of the crook he bought it from, their signatures and the frame number) when he bought the bike, and it was dated 2 days after I reported the bike stolen.
According to the paper, he paid 5.000 BEF for it (roughly £100). I basically told him "Legally it's still my bike, so I could just take it away if I wanted. However I'll give you 2.000 BEF (£40) just so you haven't lost all your money."
IMO that was pretty fair. After all he had maintained it well and it even had brand new brake pads and cables.
I drove home with my bike and the police took a copy of his purchase form. Turns out the thief signed it with his own name and had been caught before with a shed full of stolen bikes. No idea what happened afterwards, but I imagine they brought him in, gave him a lecture and then had to let him go.
Keep in mind that this was somewhere in 1997 and a police office in a quiet town. I doubt they'll want to let an officer go "undercover" for half a day to recover a bike nowadays.