Chicken jail for egg-eater: parole or life sentence?

I've got six hens; 3 Sexlinks, 1 Mottled Java, a mostly-Wyandotte and a Whoknowswhat. I have them in a fenced area with a good coop. Until fall they all laid every day, with nice looking eggs. They are well fed with Layena, oyster sell, poultry booster, and diatomaceous earth. I make sure they have plenty of fresh water, I keep the straw in their coop changed frequently and they have a light for heat/longer day during the winter (wasn't a problem last year, so...). I began to have less eggs every day. At first I blamed it on seasons changing but then I was finding sticky, gooey broken egg mess in the communal nest pretty often. One of my Sexlink's egg's had started being really thin-shelled so I thought the other hens were breaking them when laying. A couple of weeks ago my husband caught one of the sexlinks in the act of eating an egg. Needless to say I was disgusted and worried that they were all doing it. He sectioned off the coop and the "run" area and put the cannibal hen in it to see if that made a difference. I think it has because I'm getting more eggs. I've gotten a couple of eggs from the jailbird but the one today had a crack in it shaped just like her beak (it had been cut off by the breeder: boo hiss). Is there any hope for her at all or should I just give her the death penalty? Is she doing it because her eggs are so thin? Also, why did the eggs from the Sexlinks go from being a beautiful dark, reddish brown to light brown or tan color? Ok. That's it. Help?

I had used a ceramic egg in the nest to get an egg eater to stop. I would remove the egg they laid quickly but leave the ceramic. When they try to eat it they cannot break the shell and stop trying. I do not know if it would work for you hen but the two times I had an issue it did solve the problem.

My experiences with sex link hens have been either they become egg eaters or the start feather picking and eating feathers, I believe they require more protein than other breeds that don't lay as much or as often. So I would try upping their protein content, and would also make sure there was fake eggs in the nests with the hope they peck them and find they can't break them then give up. It will depend on how fixed the behavior of egg eating is in your hen whether she can be retrained.

The answer to your question is yes, it's possible that a hen with a bad habit can change. It's notoriously difficult to get a hen to give up a bad habit, but not impossible.

Culling is indeed one solution. But you may have success by persevering with your plan to keep the egg eater under careful watch. It will take time, though.

Another solution might be to try installing a bumpa-bit on her beak. It's a device that prevents the beak from closing all the way, and there's a guard that prevents the beak from being used as an implement to poke a hole in an egg. The chicken can still eat with it on. It's normally used with hard core feather pickers when all else fails.

Thin shells can start as an opportunity, then become a habit.

I'd look at nutrition first.

What is in the 'poultry booster' and how do you feed it?
Are the oyster shells given separately from the feed?
How is the DE given and why?

Your thread title is hilarious!
Once you've confirmed that she is the only one eating eggs, observing her for a time while confined and maybe adjusting her diet...
.......she may become eligible for parole.

something recommended in the serama breeder world is routinely feeding raw egg to the birds, i have done this and never had a problem with them eating eggs on their own- my thought is nutritional- more protein, possibly poultrycell for more vitamins