From here. "However, the bike owner remembered a characteristic scratch on the frame of his bike, which led him to spot it on the bike being auctioned online and report to the police"
The takeaway is of course, to mark your bike in a distinctive way in case someone takes a shine to it. Though obviously, not too much, should you ever want to sell it. Luckily, I already have one thanks to an idiot schoolkid going into the rear whilst I was slowing down to turn right a few years back. It was his lucky day that I didn't have a carbon bike.
It's only a short article - can I quote it all?
"Police in Tokyo have arrested a 53-year-old man on suspicion of
stealing a 250,000 yen bike parked near JR Ikebukuro Station in March
2015, and then selling it on an online auction site.
According to police, Tsutomu Maeda allegedly replaced some parts of
the bike before the auction so it would not be identified as a stolen
one. However, the bike owner remembered a characteristic scratch on the
frame of his bike, which led him to spot it on the bike being auctioned
online and report to the police, Fuji TV reported.
Police said that Maeda has admitted to the charge and quoted him as
saying, “I stole the bike and sold it on the online auction because I
Police suspect that Maeda had been repeatedly stealing expensive bikes to sell on online auctions."