Seller didn’t transfer security deposits?

[Alex Rodriguez]

I just purchased a multi-family rental property. The seller said they were all under oral agreements and no security deposits. After closing, one of the tenants said that they gave the previous (before this seller) a security deposit and that the seller recognized that their deposit was transferred to him. They have lost their written agreement with the seller, but they have a lease with the owner before the seller where they have a security deposit. We reached out to the seller but he stated he did not receive any deposits. Am I responsible for returning or to try to get their deposit? Or should they try to get it from any of the previous owners? The attorney is not getting back to us I guess he knows he is not getting paid to do the extra diligence.