What have you used for bait in your live trap? You might try setting it while the remaining hen is NOT in the coop. Raccoons love marshmallows. Try those for bait, and see what you get.
The first year we were here, we lost a bunch of hens to raccoons. We had fixed up a room in the barn, covered with chicken wire, etc., and the coons kept finding holes they could reach into and get ahold of parts of chickens. They pulled bits through the holes and ripped our poor hens apart. Then I'd find the bloody remains in the morning. We were both working long hours, and didn't know much about raccoons at the time. We got a live trap, caught a couple in it with sliced apples for bait, and my DH shot a couple of them, in the barn.
We built a new coop as soon as we could, moved the hens, and had no more trouble with them until this year, 11 years later. This year, we lost 17 guinea keets in 4 days, to a band of raccoons. The 2 guinea moms would not go inside with the babies at night. One group was over 3 weeks old, we thought they were home free. then the raccoons appeared, and she lost all but 3, in 4 days. The other mom only had 3 babies, they hatched just before the other started losing hers, they didn't last 48 hours.
I trapped 4 in less than a week, using marshmallows for bait. We haven't lost any more since, I'm hoping we've cleared them out for now. But I think there's one more at least, a big one. I mean, of the ones who've decided this is the buffet. I know there are always more in the area, but they don't always decide that this is the cafeteria.
Good luck, I hope you catch the culprits.