Questions about Kinloch Missouri

I recently went to urbex at the abandoned police station in Kinloch (5650 jones ave). It was a learning center in 2012 and became a police station in 2015 going abandoned in 2018 or after ( not quite sure on that date). When I was there on my first visit I heard someone knocking on the ply wood window of the side entrance and was very disturbed by that moment resulting in me now wanting the floor plans as I want to have a general scope of the building before I have a chance of getting jumped by a homeless dude also I want to know why are there 3 buildings and a weird structure hidden in some trees near the parking lot and the story on the yellow truck out front. It would be very helpful if someone could answer my question

edit: also I do not believe it is a person since that smell of mold is very strong and the condemnation letter is very convincing. There is also almost no way someone would have been able to see me since I didn’t even enter the building and I was there for maybe 3 minutes. Although I want to make sure I’m safe since I’m going in alone.