At my friend's house, we laid out the wallet's contents to find an email or phone number. Bad news: The wallet belonged to a student from Brazil and had only school IDs showing he lived in Rio de Janeiro, some credit cards (American Express Platinum) and $370 in cash, including two $100 bills. Obviously, he was visiting and perhaps breathed in the sweet air of American freedom to the point of a momentary lapse of wallet judgment.

"He must have been muy borracho," I mused, Spanish for "very drunk."

We found a name and email on the back of a picture, then realized that came from the photographer.

CSI Katonah continued its methodical way. A call to American Express could probably get a message to the guy. Finally, amid the detritus of an overstuffed wallet, we found a piece of paper with a Westchester County address and phone number. A reverse look-up showed we had an unlisted number. Since it was almost 3 a.m., I decided to wait until the morning to call. If that failed, I would call American Express as a way to reach the guy.

Then I had the brilliant idea of googling the fellow's rather distinctive name. I did that and -- bingo! -- I found him on Facebook in Brazil. I sent him a note at 2:44 a.m. with the subject line, "I found your wallet on the Metro-North train tonight."

On New Year's morning, after 9 a.m., I called the number. A man answered, sounding surprisingly alert. I asked for the wallet owner and explained the situation. The man gratefully took my name and phone number said he would check. The student was still asleep and the man doubted he even knew he had lost his wallet. He expressed his gratitude.

"I'm happy to help a carioca," I said, using the term that people from Rio de Janeiro use to describe themselves. I've visited Brazil and am a huge fan of the country's music, I added.

About an hour later the man called back and we arranged a handoff at 1 p.m. at the Katonah train station. I wondered who would show up. My friend and I clomped through the snow to the meeting place, and sure enough, found a tall, curly haired young man with three or four other young people. I gave the student the wallet and I got a bottle of Italian wine for my efforts, a very thoughtful gesture.

The Raiders of the Lost Wallet stamped "case closed" on their file book, having enhanced relations between the United States and Brazil in a direct people-to-people way.

Coda: I had to chuckle at the gift, because I also got a bottle of wine as a thank-you several months ago when I returned a cell phone I found on the train to the owner. Doing mitzvot (good deeds) is going to turn me into an alcoholic if I'm not careful.