Hmm... tricky position to be in. What will sending him to jail really accomplish? There are 2 young kids who have lost their sister, who will now wonder where there daddy is. You are turning a family, into a single mother household. I guarantee you that Derek has gotten the message, he has no lessons to be learned by going to jail.
I lost a child last year, though no fault of my own, it's a devestating ordeal. If it had been my fault, I can only imagine the pain involved.
I'm not saying that he shouldn't face reprecussions for what he did. He should lose the badge, do some community service, or something else. Sending him to jail will just further hurt the innocent victims in this tradgedy.