I decided to bring this thought over from the other spoiler thread.
I am thinking (and someone might have mentioned this) that the husband pulled the plug on his own, thus killing his wife. He lied about it to Sara so she is pissed. Maybe she wants him to pay for killing his wife (even though technically she was brain dead anyway). So since Sara is no longer a CSI and can't investigate the case perhaps thats where Greg comes in. She recruits him to help her. This is speculation but it is plausible.
Okay, let me speak from a nurse's perspective:
What if Pam Adler had no living will,maybe that is why she is still attached to a breathing tube and a feeding tube.(I see both in the promo) with IV lines etc...Her husband Tom finds someone else, maybe he has fallen in love with someone else.
Problem: He won't collect her life insurance to assist with the hospital bills if he pulls the plug, but can't stand for her to suffer any longer, he also wants to move on with his life, but the debt of her years of hospitalization would crush him financially.His love for her is stronger,maybe a day in court took away his rights to make her decisions, especially if he wanted to pull the plug,he does it anyways and tells Sara he did it because he loved her so much but Sara through Gregg's investigation discovers that Tom is involved with someone else and did not disclose this to Sara. But his true reason might turn out that he was tired of seeing his wife suffer in a vegetative state.
My thoughts...something along this train of thought.