I'm sorry you're going through this.
I would follow up the email with an actual letter sent via snail mail (possibly certified mail or return receipt) to the DA's office so that they have something on paper (your letter) and you have something on paper (the return receipt). Also, make sure that if his parole is denied, you are notified well in advance of any future parole hearings.
How long has this guy been in prison? What was the original sentence and how much of it has he served?
Take care
