A preschool teacher working at Stanford University was arrested for murder this week as her students napped, according to local authorities. Diana Ornelas of Santa Clara was one of two people arrested in the fatal shooting of Oliver Waterfall on April 11. Dennis Novoa, 27, was also arrested in the investigation, which kicked off after 24-year-old Waterfall’s body was found on a hillside off a highway. It’s believed that both were known by Waterfall, and that the shooting incident was of “a personal nature,” according to the Santa Cruz County Sheriff’s Office. Ornelas, 22, was employed by the Children’ Center of the Stanford Community, a nonprofit childcare center, and has since been terminated from her position, a university spokesperson told the Stanford Daily. “The arrest happened at naptime, and outside of the perimeter of the CCSC campus. Children were not present when this occurred, and it did not disrupt operations,” the spokesperson added.