In my experience, I generally tell all people who ask me this question to NOT contact the DA. Sometimes people even ask me about contacting the Judge and I tell them never to contact the Judge. I digress.
The real reason I tell people not to contact the DA is because they have no idea how the DA will use their conversation against their loved one. For example if you were to say that your cousin knows better, the DA could turn around at sentencing and say to the Judge, even his family admitted to me on the phone that he knows better. Hit this clown tough, he KNOWS BETTER.
Contacting the DA is generally a bad idea. I have ever only had one occasion where it was to my client's benefit.