Porcupine wire is preventive, not murderous, as far as I can tell. I can understand that choice.

Could your same friend who was followed by Mr. Raccoon bring more sardines and wave them around the hole, thus luring the raccoon out if he's in? Then you could know that he's gone before you put up the wire.

I am willing to assist.

Dogs and nature abhor a vacuum.
http://geaugadoggy.wordpress.com