reporter: under cross-examination, even brad the escort said peterson had told him how much he loved his wife. in his e-mails unlike most of my clients he indicated that he had a great relationship. most clients don t want to say anything about the relationship. he indicated he had a warm relationship with his wife and nothing would ever destroy that. reporter: michael hadn t killed kathleen, the defense argued, and he certainly didn t kill family friend, elizabeth ratliff. they called their own medical expert who reviewed her autopsy reports and said it wasn t a murder. is blood in all of the ventricles of the brain consistent with a stroke from natural causes? expert: it is consistent. reporter: then, there was the mount everest of the case: the forensics, explaining to the jury all that blood in the peterson stairwell. the defense would call dr. henry lee to the stand. reporter: the defense called celebrity forensic expert dr. henry lee, of o.j. case fame, to show the