On June 2, 2007, the body of 36-year-old Hugues de la Plaza was found in his locked San Francisco apartment. He had been stabbed in the neck, chest and stomach. His apartment was covered in blood, and the scene seemed to have all the characteristics of a homicide, but there was no sign of a struggle, no sign of anyone else’s DNA at the scene, and no image of an assailant on nearby security cameras. “48 Hours" correspondent Maureen Maher reports. This classic "48 Hours" episode last aired on 6/19/2010. Watch all-new episodes of “48 Hours” on Saturdays, and stream on demand on Paramount+.