CS was a plant in the hotel long before the crime.

It hits you like a truck. Custodial Staff has only been working for the hotel for a little over a month. CS must have started to work at the hotel to make sure that this plan went off without a hitch - suppose that's a new lead to explore whenever you head back to the hotel. You decide to do some quick inventory management: the clipboard goes into your desk as evidence, you set the recycling poster beside your desk for now, and pick up your phone.