Police investigating the fatal mauling of a pregnant San Francisco Bay Area woman by her pet pit bull say they don't know what caused the animal to go off.
Pacifica police completed their probe into the death of 32-year-old Darla Napora on Thursday.
Capt. Dave Bertini tells the San Mateo County Times (http://bit.ly/qm6tJ0) a necropsy on the 2-year-old pit bull named Gunner turned up no diseases or conditions that would explain the Aug. 11 attack. The dog was also apparently treated like a member of the family and had no history of violence.
Napora was found mortally wounded by her husband, Greg. She died of massive blood loss and shock.
Officers killed Gunner when he escaped from the back yard while they were investigating the mauling.