I boat (used to?) on the Chain O'Lakes in Northern Illinois.
The boat was stored in a private locked pole barn with many other boats which didn't seem to have been touched. The door was forced open.
The police don't seem to think it's a big deal, the guys finger prints are all over the place and they grudgingly accepted a part to test.
I agree it must have taken some time. Some parts were carefully unbolted, others ripped off.
A serious concern is where did all those valve cover nuts and washers go, down the engine?
Thanks all for your concern, keep your ears open!