What can I do if someone entered my apartment without permission and left a used condom on the toilet?

My roommate and I left out apartment home for the whole weekend and locked our door. We share the apartment with 2 other people which stayed while we were gone. Our room is separated from theirs and we have a living room and kitchen that connect both rooms. We all have separate leases, which in my opinion, makes my roommate's and my room our home. Can we press charges to the leasing office, since the condom is used and it can be an HIV hazard?