Isn't it delight to follow the path of previous idiots when it comes to butchered home wiring?
I once wasted half a day, and nearly drove myself, mad at the MIL's house. She had a "pro" come in and rewire the kitchen during a remodel, and was now experiencing shocks, when standing on the metal door sill, and touching the light switches. After reviewing any rational potential problems, I finally determined that the bastard had shorted out a Romex cable while yanking it behind old wire mesh plaster lath. He couldn't keep the breaker from tripping, so he opened a junction box and cut the ground on the damaged cable. The best part is that he actually took the time to carefully cut the ground inside of the jacket of the damaged cable and hide the break, so that it was impossible to even see what he had done. This left everything from the wire lath, to metal electrical boxes and switch cover screws in the kitchen, with varying voltages available to the touch. It could of killed somebody, but at least the breaker stopped tripping.