First, you talk with the good Doctor who has been a little "busy" with extracurricular activities.

Affair with Sophia? He broke it off. Ah. So he WAS sleeping with Sophia, Leda and his wife.
Sap in truck? There was a body in my truck? It must be a frame-up.
Relationship with Leda? I have a roving eye. (I don't think it was his EYE that was roving).
DNA? yes, but it didn't match anything.

OK, now the loving wife. Or was that angry wife?

last drive the truck? never. It's a stick shift.
Leda? nope, is she another one of his chippies? (guess she isn't a blind woman)
DNA? yes.

Her DNA doesn't say anything either. Guess it's time to chat with Leda!

CSI Crime scene Investigation Walkthrough