Speaking as a lawyer, Marshawn does not need to say anything. His lawyer is correct in making ML not even speak with the police yet. There is procedure here and ML should say nothing. If he was driving, he should definately say nothing. Take the 5th and let the police prove it. If he was not driving, I would still counsel against saying anything, plead the 5th per any obstruction/consipracy charge.
At this point, DUI is off the table, as there is no physical evidence. So it is a simple hit-and-run. So, you shut up for now.