I am sorry for your loss in any case.
With a $50 cordless angle grinder, it really doesn't matter what someone has on it since it can be taken off in seconds to minutes, be it a padlock, lock over the cover, etc.
I use multiple theft deterrents on my rig, which won't stop a determined "lab administrator" looking to expand, but it will slow them down:
1: The BAL X-chocks I have have padlocks through them.
2: Padlock on the latch, and a lock on the tongue.
3: A security chain through a set of wheels.
4: Locking lug nuts.
As of now, I have a fifth measure -- my trailer has sunk so much into the sugar sand that it will take a heavy duty wench to break it loose as of now.