her death was linked to her addiction. >> she did have a drug problem. she had an addiction to opiate medication, prescription pills. >> an overdose would mean no crime, just a regrettable death or even a suicide. but then, six weeks later, something that changed the entire focus of the investigation. emily's toxicology report came back. >> the results came back clean. she wasn't under the influence of opiates at the time of her death. >> so it wasn't an overdose? >> it wasn't an overdose. >> no trace of the opiates she had been abusing. there was nothing in her system, no alcohol. so investigators had to take a look at the case, starting with the photos of bruises on her body. police saw a bump on her head, but during the medical exam, the medical examiner found more. >> she had trauma to all four sides of her head. >> possible those injuries could have occurred while alex was dragging his wife out of the tub?