Since the explosive was located right up under the lock box, the only reason to thread the wires through the collar itself is to keep the device from being cut off with some sort of torch.
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?