After 40 years, a suspect has been arrested in the murder of Patricia Carnahan at a South Lake Tahoe campground in 1979. Harold Carpenter, 63, was identified after a rape kit from a 1994 sexual assault in Spokane, Washington, was tested and his DNA matched evidence collected from the victim's body. This arrest is a major breakthrough in a cold case, thanks to the power of DNA technology and the dedication of law enforcement.