She's between a rock and hard place in that respect. If she were to ask forgivenes...what would it be for? Lying maybe...but to go further it would then be an admittance she had a role in CAley's death....and she's not about to confess that. Though if she did she couldn't be tried again I understand. Still she's in a tough spot...IF, and I say that lightly, she's even got a conscious, which is very much doubtful. I think that got fried long ago.
If Casey wants to confess her sins and then ask for forgiveness, she can do so with a pastor, who is bound by confidentiality.
Casey is a free woman who cannot be tried again because of the laws of double jeopardy.