Q: What should a gabbai do with items left in shul?

A: Items left in shul should usually be left in place, as the shul is considered semi-secure; most likely the owner will return there to look for the item. If the shul is not secure [or if there is a need to clean the place] the items should be moved to a secure and designated lost and found area (Igros Moshe, O.C. 5:9). The same is true for a beis medrash, mikveh, etc.

If the item is left there for a long time and seems abandoned, we can assume that the owner abandoned hope of reclaiming it (yei’ush) and anyone can take it, even if the item has a siman. However, the shul or beis medrash does not acquire the lost item automatically through chatzer (see C.M. 262:5; M.B. 154:59; Pischei Choshen, Aveidah 9:13).

Current Poskim recommend that the shul post a noticeable sign that anything left in the shul beyond a certain length of time becomes hefker and the gabbaim will do as they please with it (see Igros Moshe, C.M. 2:45b; Hashavas Aveidah K’halachah 7:1-4).