An instructor at Saint Mary's College in Moraga and City College of San Francisco was found fatally shot in the backseat of a vehicle in San Mateo County Saturday night and an Oakland man has allegedly admitted to the killing, officials announced Monday.

Just after 11 p.m. Saturday, a San Mateo County sheriff's deputy located a vehicle in the parking lot of Montara State Beach and conducted a security check. As the deputy approached the vehicle's driver, he noticed an arm extending out from a blanket in the vehicle's backseat, according to the sheriff's office.

Sheriff's deputies found the body of John Alfred Dennis Jr., 59, of Oakland, in the blanket and emergency personnel pronounced him dead in the parking lot.

The vehicle's driver, identified as Troy Thomas, 44, of Oakland, was detained, the sheriff's office reported.

About an hour after locating Dennis' body, the sheriff's office contacted the Oakland Police Department and requested that police conduct a security check at an Oakland home, located at 8011 Hansom Drive, in connection with the death, Oakland police Officer Roland Holmgren said. Responding officers discovered evidence of a crime at the home and homicide detectives were called out to investigate. Thomas allegedly admitted to murdering Dennis and said he had planned to dispose of the body, according to Holmgren. Thomas was arrested on suspicion of murder and Oakland investigators will present the case to the district attorney's office.

The San Mateo County coroner's office conducted an autopsy that revealed Dennis was killed by a gunshot wound, Holmgren said.

According to the City College of San Francisco's Web site, Dennis had been a faculty member since 1980 and was part of the Social Sciences and African American Studies departments. Dennis received a bachelor's degree from University of California, Santa Barbara and master's degree and Ph.D from Stanford University.

Dennis was also an instructor at Saint Mary's College. Ronald Gallagher, president of the college, issued a letter today to the college's community reading, "With great sadness I share with you the news that longtime faculty member and form director of the High Potential Program John Dennis was victim of a homicide this past Saturday. Over the coming days we will all struggle to come to terms with this senseless act, confront the loss of John to our community, and for those who knew John, deal with the personal grief of his absence."