It is prohibited to buy from a robber or a thief the merchandise which he robbed or stole. And there is no difference [in this between] Jew or non-Jew, for also the non-Jew has the prohibition of robbery and theft even from his fellow non-Jew and it is one of the seven mitzvos that were commanded to them. It is a great sin to buy from the robber or from the thief, for it strengthens the hands of sinners. About this it is said, “One who partners with a thief hates his own soul; [he hears the rebuke and tells nothing.]” It cayses the robber to rob more [items] and also more robberies, but if he didn’t find a buyer he wouldn’t steal. Even though that it’s possible for him to go with the stolen [merchandise] to a place where they do not know him [and sell it there], it is not all that common.
If the buyer intend for the good of the owners, to return to them when they repay him his money, it is permitted. [Presumably replacing the old item at pawn rates is preferred by them over buying a new item at full price.] But specifically when it is impossible for the owners themselves to save the item.
Similarly, it is prohibited to accept as collateral something which appears to be robbed or stolen.