(Fotolia)

A thief came clean and returned $800 with interest along with a note of apology for robbing a Michigan convenience store about 30 years ago.

On Monday, the mystery culprit delivered a handwritten letter to 24 Hour News 8 and $1,200 cash to police.

The writer, in an error-filled note, admitted to breaking into what was then the Middle Mart north of Middleville in the 1980s.

"I can't begin to say how sorry i am but have lived with this guilt too long. If you do find him (the owner), please tell him that I was afoolish stupid man when I did that and i am sorrie (sic)."

Police tracked down the former owner of the store — it has since been sold — who confirmed the theft. The cash will be returned to him, police said.

"He was shocked just as much as everybody else was, 'cause this just does not happen every day," Barry County Undersheriff Bob Baker told News 8.

Police said they won't investigate the theft.