I had my koi's eaten also and found it to be in the city raccoons. I got
me one of these
http://www.harborfreight.com/cpi/cta...emnumber=90218
and baited it woth marshmellows. But be warned you will have to haul 20 to
30 raccoons (maybe more) to a very far away place (at least 20 miles) and
release them.