For years, a mysterious Auckland poop bandit has been terrorising the suburbs of Beach Haven and Birkdale by sneaking into people's homes and defecating on their pillows.

Now the culprit has finally been revealed - Jack, a dog.

His owner, Rick Didham, admitted his "extremely intelligent and cunning" pet's crimes in a post to a local Facebook page, saying he has been too embarrassed own up to this before.

"I'm so embarrassed and ashamed to say this but Jack has somehow gotten out of the property more than once," he wrote.

"Apparently he has been caught by more than one of our neighbours sneaking in their cat door and doing number twos on people's bedroom pillows."