I got my wallet stolen by a pickpocket while getting on a light rail train in Dublin on St. Patrick's Day last year. I had just purchased a train ticket and put my wallet back in the side pocket of my cargo pants. Someone must have been watching and when I was boarding the train amidst a crowd of people, I felt something near that pocket and noticed my wallet was missing. I knew who took it because he was right next to me, so I told him to give it back. He said he didn't have it so I started reaching into his pockets and pulled out a cell phone. He told me to give it back so I told him he'll get it back when I get my wallet back.
Another guy came over and asked what's going on. I told him the guy stole my wallet. I don't remember what the second guy said but it made me suspicious of him too, so I started reaching into his pockets and he said, "Oh I'm a part of this too now?" The first guy then handed me his jacket and backpack to search through. As I was looking through his stuff, the second guy got off the train at the first stop. I decided to stay on the train with the first guy, but then realized that the guy who had just gotten off had my wallet. The first guy got off at the next stop but I grabbed his shirt to stay with him and got off the train. He handed me his jacket and backpack again, and then tried to run away even though I still had his phone. I left his stuff on the ground and chased after him. He zig-zagged back and forth through an intersection with cars honking at us, it was ridiculous. Eventually I caught up to him enough to grab the back of his shirt with one hand and punch him in the head a few times with the other. He got loose and ran towards the sidewalk, but I shoved him into the wall.
We happened to be right across the street from a police station at this point, so they came outside and brought us in. Turns out the guy had just had a court hearing that same morning for the same thing, so they kept him there and he spent the night in jail. They said there are these Romanian pickpocket gangs that travel around Europe and once they get caught enough that they are facing jail time, they leave and go to a different city. The police said that while I didn't get my wallet back, I at least caught a criminal and prevented him from stealing other people's wallets that night.
I got a facebook message from someone in Dublin who found my wallet on the train. He turned it into the police station and I picked it up a couple days later. I had about 110 euro in cash that was gone as well as my debit/credit cards and my license. Fortunately, I still had my old license in my wallet, so the guy who found it was able to look me up on facebook. I broke a finger when punching the guy, but I got all the cards replaced, my finger healed, and I came home from a vacation with a story to tell.