medical examiner joni mcclain would perform the autopsy. to mcclain, the evidence pointed to sexual assault and murder. she found bruising on isis' head and body, hemorrhaging in the brain, and a laceration at the entrance to the vagina. in her final report, she called it homicide by multiple blunt force injuries. ernie lopez was charged with aggravated sexual assault. and, after a short trial, he was found guilty. before sentencing, medical examiner joni mcclain testified that the baby died from this violent assault. lopez was sentenced to 60 years in prison. >> you know, sometimes, it just hits me: "man, i'm in prison." i never thought i would be in prison, never in a hundrediok years. >> thompson: for the past year and a half, frontline, propublica and npr have been investigating medical examiners and the field of forensic pathology. we found a broken system in which the most basic principles of science and investigation are often ignored, with no national standards of any kind. >> it amazes me that such an important aspect of our govern