Within the past week, Vilkin said that Upton had threatened him and that he called the San Diego Sheriff's Department to report it. That incident was the reason he had a gun with him when he went back to his property Thursday, said Vilkin.
Vilkin said Upton was obsessive about privacy and had demanded he not cut the greenery, even though Vilkin said the greenery is on Vilkin's property.
10News called the sheriff's Homicide Unit to confirm Vilkin's story, but they said they were not commenting on the matter.
On the day of the shooting, Vilkin said he was trying to cut some shrubbery on his own property, but Upton came out of his house and confronted him.
According to Vilkin, Upton pulled out a gun and told him to stop cutting.
Vilkin, who was also armed, said he pulled out his own weapon and shot Upton once in the stomach. To his surprise, Vilkin said Upton kept coming at him and that's when he said he shot Upton gain, this time in the head.
"I shot him; you know, I predicted him to fall immediately because this is a .44-caliber Magnum. He did not, he did two or three steps toward me and then I shot him in the head," Vilkin said.
"It was self-defense; I did not go to him. He came to me threatening and pulled a gun at me. I did not go to him. I stayed away on my property," Vilkin added.