UC Davis students John Riggins and Sabrina Gonsalves fail to show up at a party Pictures On Dec. 20, 1980, two students from the University of California at Davis, Sabrina Gonsalves and John Riggins, went missing. It would take more than 30 years to solve the mystery of their disappearance and finally close the case. "48 Hours": The Sweetheart Murders Credit: Cecelia Riggins