Bava Batra 45 - The Chazakah of a Craftsman
A craftsman does not establish a chazakah in an article known to have belonged to someone simply by having it in his possession.
Said Rabbah, "This is only true when the original owner gave the craftsman the article in the presence of witnesses. But if not, the craftsman could have denied receiving the article altogether, and is believed on the strength of the "Why would he lie?" argument.
Said Abaye, "If so, he should be believed even if there were witnesses, for had he wanted to lie, he could have said that he returned the article."
They differ about the following question: if someone deposits an article with his fellow with witnesses, does the custodian need to return it also in the presence of witnesses? The accepted answer is "no," which means that Abaye's ruling prevails.