Wasn't at Kessler last weekend but I've done two overnight investigations there in the past couple of years and that place has form for shadow figures, particularly near the old millrace. Second visit I caught something on the full spectrum cam that I still can't fully explain away and I've tried pretty hard to debunk it.
That said I'd want to know exactly where you were standing and what the lighting conditions were before I get excited. Too many people see "shadow figures" that turn out to be their own shadow bouncing off dust or moisture in the air. Happens constantly on investigations.
What time was it and were you using any equipment or just eyeballing it? If you've got footage post it up, lets see what we're actually dealing with before this turns into another thread full of people convincing each other they've cracked it.