Troy Roberts reports on the case of Pvt. John Needham, a decorated soldier who was Medivac-ed from Iraq and later diagnosed with traumatic brain injury (TBI) and post-traumatic stress disorder (PTSD). Investigators say John beat his 19-year-old girlfriend to death with his bare hands - and while John took responsibility for Jacque's death, he remembers little of the crime, recognizing only that something inside him snapped. 48 HOURS MYSTERY explores the murder of Jacque Villagomez, as well as whether John's TBI and PTSD might have played a role in her death.