I was riding home for lunch and right on the corner of my block a dude was bent over a bike attached to the pole. When I stopped and looked to see what he was doing, I saw that he had a short piece of rebar and was using it to leverage out the U-lock. He was about 6' tall, with polarized glasses, a beard and a big hooded blue puffy coat. The bike was a newish, standard-quality silver mountain bike and there was a red helmet attached to it. It looked sort of feminine and he definitely did not. So I asked him why he was doing that (in french) and he said "I lost my keys" (in accented english). I stood and watched him and he definitely was watching me. I was maybe 20' away. He succeeded in breaking the lock. He picked up the rear fender he had knocked off and the helmet and quickly rode away. I followed him, but he lost me heading the wrong way on St. Laurent. He rode on to the sidewalk and since I am trying to abide by the law on my bike, I hesitated and got blocked by oncoming traffic.
This whole episode has left me with bad feelings. I really feel like I should have stopped him. The problem and most reasonable people agree with me, is that I had no way of knowing for sure that he was stealing the bike. It could have been his girlfriend's who lost her keys and he was pissed about having to go get it. But now looking back, I'm pretty sure the guy was a thief and I should have just jumped in and beat him with my own u-lock. It doubly bugs me because this was right on my block and it would have been a very good opportunity to send a message about where junkies and thieves should and should not feel comfortable getting up to their shenanigans. And finally, I'm bummed that the guy got away from me. There was a time when I could have stuck with him all the way to hell and back, but I'm getting older and careful and I was aware that I only had 45 minutes left on my lunch hour. If I had followed him to an address and it turned out the bike was stolen, then I could have left a sign on the pole and the police could have tracked the dude down.
So what should I do next time? Get more aggressive and ask more questions? Pretend I know whose bike it is? Just prevent anyone trying to unlock a bike with a piece of rebar as a general rule?