there are people who do out of narcissism and a lack of empathy and truly missing a super ego, missing their moral compass, really could commit a completely heinous crime. no, i think it can be there. what i do know about the human mind is one can so circumscribe, so be in denial and compartmentalize and do heinous things and lie to themselves that i didn't do this, justify it to themselves. we see this all the time. >> dr. gail saltz, thanks for your insights. >>> the key to casey being found not guilty may lie in the prosecution's inability to prove exactly how her daughter died. we'll hear from our crack legal team when we return. ♪