Prohibition of theft?

I'm in a boarding school as part of the Ulpena, and the girls who attended last year left us "souvenirs" in the closets. Clothes, bedding, socks, etc.
They had already finished the ulpana, but they didn't bother to clear away the belongings. It was obvious that the items had been forgotten.
One of the girls in the current room was longing for a dress left over from the previous girls, and I asked if we should make an effort to locate the owner of the dress? And maybe it's her responsibility, and since she didn't come back to pick it up, the items are being misappropriated? It should be noted that the Ulpana collected the items from the boarding schools at the end of last year, photographed them, and made it clear that anyone who didn't pick up their belongings would have them thrown away, but for some reason they apparently didn't notice these items (which didn't appear in the photo).