>> this really becomes a case about science, doesn't it? >> if the science didn't work, if the jury didn't understand it or didn't buy into it, it was gonna be a not guilty. >> reporter: dr. diane scala barnett, the coroner who had performed the autopsy on dana's exhumed body told the jury she'd been able to get a better look at dana's skull than the first coroner. >> i saw separate fractures and the pattern of fractures only after the bone was cleaned. >> there were three impact patterns, three distinct patterns. >> and what would have caused those? >> a beating. >> a beating? some sort of bludgeoning instrument -- >> absolutely. >> unknown, was used? >> absolutely. >> but there's no question there were three impact sites on the skull? >> no question. and this was not at all consistent with falling out of a car. not at all. not in my experience. >> "y" shaped incision -- >> reporter: it was gruesome testimony for brittany to sit through. >> the one thing i wasn't