For Your Consideration - Ghosts..

The history-
On october 2016, our co worker opened our office at 6AM and saw a 6 foot tall shadow in the doorway, with no one inside. we've had some odd things happening like footsteps on a concrete cieling...lights on and off. so, I put an audio recorder in various places so no one could mess with it for a week or so afterword. This is the ONLY thing we caught. it was on a Friday night at 10PM when the office should have been empty. lots of silence, but you'll notice it when you hear it. so, should we be worried? :)