My wife breeds chickens and as other members already posted,
solution to your friend's brother's predator problem starts with a secure enclosure/coop for the chickens. (Or does he plan on guarding the coop every night?)
Send him to Backyard Chicken forum, world's largest online forum on anything chicken related, to learn how to "predator proof" coop for chickens (Or Google "How to predator proof chicken coop") -
https://www.backyardchickens.com/threadloom/search?keywords=predator+proofing+coop&tab=0
We initially enclosed 12'x12' corner of the pole barn and had to deal with predators, mainly racoons and after learning about predator proofing chicken coop, built 24'x8' coop with 1/2" wire fabric and no more predator issues.