Have to wonder if all 4 locks were locked. Did the authorities pick all of the locks? Did they find the key? Did they cut his head off?
Little detail as to how the collar was eventually removed.
It is dangerous to approach a body that is dead because of a known collar-bomb. What if there had been a second device with a delayed timer?
I am no expert by any means, but could the wires be tapped into and a bypass loop configured so that when the device and wires were cut the circut would remain intact?