So sorry for your loss! I wouldn't just worry about trapping the predator, because even though you may get this particular predator, there will always be more. I would focus on predator proofing your coop. (1/4" hardware cloth covering every bit of the run and all ventilation areas, as well as burying the hardware cloth underground, putting rocks or bricks around the run, and making sure there are no open gaps bigger than a 1/2")
good luck and hope you get your chickens back soon!