The Los Angeles Times reported Saturday Michael Vilkin, 61, of Vista was arrested Thursday in the slaying of Upton, a 56-year-old filmmaker best known for his efforts to bring the plight of orphans in Romania to light. Vilkin is to be arraigned Tuesday.
The San Diego County Sheriff's Department had not disclosed a motive for the shooting, but the Times said the men may have been involved in a property dispute.
Upton's body was found Thursday morning outside his home, located next to a vacant lot reportedly owned by Vilkin.
KGTV reported Vilkin told the San Diego TV station he shot Upton in self-defense after the filmmaker pulled a gun on him. Vilkin allegedly said Upton was upset he was trimming trees on his property.
The Times said Upton won an Emmy in 1990 for an after-school special on teenage promiscuity and later worked to publicize the the brutal living conditions of Romanian orphan.
He also was known for his efforts to focus attention on social problems in the United States, including those of seniors, the abused and the disabled.