Dom said in the original article the killer might not know. Why would you want another ben or stacey on the show who was a cold murderer and will probably get sent down? if the murderer is someone who is staying in the show they need to show remorse and since they havent then i presume they don't know.
Aw its obvious jay still loves abi and theres a reason for the split more than him not wanting to go with her. He wouldnt have kicked off like that and been so nasty to abi if he didnt