What happen when electric passes through the dead body?
A common Biology experiment performed in high school is in passing electricity through the legs of a dead frog. When that happens, the frog legs draw up. When the electricity is shut off, the legs extend back out. When the electricity is turned on off on off on...the legs appear to be kicking.
If your dead body is not decomposed, electricity passing through it would likely cause the muscles to contract just like in a dead frog.