In March 2007 pensioner Peter Jürgensen had his wallet stolen from a supermarket in Walsrode, Lower Saxony in west Germany.
The 73-year-old lost €350, his credit card, identity card and photos of his grandchild.
He only noticed the loss a few hours later and headed back to the supermarket, the Bild newspaper reported on Wednesday.
The former tennis coach applied for new documents and forgot about the theft until now.
But six years later he received an envelope with his stolen wallet inside and a letter apologizing.
“Greed drove me to taking the wallet,” the thief wrote. “I have become a confessed Christian. The holy spirit has called upon me to repair the damage.”
The anonymous man also put an extra €50 in the wallet to apologize.
Jürgensen said: “Everything was in the wallet as I left it. I thank the man for his belated honesty.”
The letter began. “I found your wallet in Edeka Walsrode and wanted to hand it in.”
It was signed with the initials M.L.