Property rooms or evience rooms are usually in a police station. They are basically secure rooms where vital evidence is kept until it can be used in court, or it can be evidence where an offender has not yet been arrested such as a vital piece of evidence recovered from a scene of crime. The rooms are usually very secure as most of the evidence would be key in an investigation to present in court. All evidence taken in or out presumably has to be tagged, logged and barcoded. And to take something out you have to have prior permission from a superior it is believed.