From OP's math, friend started with 15, lost 10, then after OP found the hole, apparently friend didn't fix it. OP put up game cam that night and caught a picture of the raccoon with another dead chicken, so it appears that friend has lost 11 to this raccoon so far.
I'm excited to hear
@jnicholes' account of how camping out to ambush the bandit went last night. Camping out in this heat during mosquito sounds pretty miserable, but hopefully they fixed the weakness in the run fencing last night and prevented more chicken deaths and ended the bandit.