Money Out of the Bank

Question

I recently asked a friend of mine to deposit a check into my account. He filled out the information needed on the deposit envelope, but accidentally wrote the wrong branch number on the envelope. As a result, the money got deposited in someone else’s account. After two weeks of herculean effort to retrieve these funds, the bank was finally willing to return these funds to me. This incident caused me to wonder if the people who accidentally received the money were responsible to return it. Can the rov clarify this for me?

Thanks.

K. Y.

Rav Auerbach 

In such a case, the person who received the money through an accidental deposit into the wrong account is obligated to return the money as part of the obligation of hashovas aveidah, returning a lost object. A person who has a lost item in his hands is obligated to return it, and if he does not do so and uses the lost item, he is considered a gazlan, one who has stolen. From what I understand, modern-day technology allows a person to see every check that was deposited into his account. Therefore, assuming the people saw that your check was mistakenly deposited into their account, they should have made efforts to return the funds to the rightful owner.