A security system with a security container and an electronic lock circuit is used to securely store mechanical keys or other valuable items. Items to be protected are placed in a secured location in the security container. A detector of the security system detects whether the items are indeed in the secured location, such as by means of receiving signals from a transponder attached to the items. The security container is locked only if the items are detected to be in the secured location. Audit trail records for the locking and unlocking events of the security container may be transmitted to a device remote to the security container for analysis. A monitoring device with a location identification device, such as a GPS sensor, may be attached to items to be monitored for tracking locations and activities of the items.