“Do I have to return it, or just notify the tenants?” asked Mr. Klein.
“You need only notify them, and they are responsible to collect it,” said Rabbi Dayan.
“I’ve tried that and they haven’t come,” said Mr. Klein. “Can I give him a deadline by which time they must come?”
“Some contemporary authorities rule that one who finds an item can give the owner a deadline,” replied Rabbi Dayan. “If the owner was informed and doesn’t come to pick it up by a certain reasonable time, it can be taken out and left hefker.” (Hashavat Aviedah K’halacha 3:6 citing Hagaon Rav Nisan Karelitz, shlita; see also C.M. 319:1.)