An organization needs to plan for a situation like the one in this chapter before it happens and train people accordingly. In my personal experience, I have found that most, if not all, private sector businesses are very lax in this area of physical security. You might try to approach the problem from the other end, putting the burden on your company's own employees. A company without 24-hour guard service should tell its employees that to get in after hours, they are to bring their own keys or electronic access cards, and must never put the cleaning people in the position of deciding who it is okay to admit. Then tell the janitorial company that their people must always be trained that no one is to be admitted to your premises by them at any time. This is a simple rule: Do not open the door for anyone. If appropriate, this could be put into writing as a condition of the contract with the cleaning company.