-- intro: At age 56, documentary film maker and philanthropist John Upton was dead.
The father of three went outside his home on the morning of March 2, 2013, when he was shot in his midsection and then the head.
But Upton’s killer wasn’t a stranger. His next-door neighbor Michael Vilkin shot him with a .44 magnum gun and called the 911 shortly after.
While Vilkin claimed the shooting was in self-defense -- because he feared for his life -- Upton’s neighbor was found guilty of murder.
Click through to see how a simple dispute over brush and trees between neighbors John Upton and Michael Vilkin ended in death.
quicklist:1title:John UptonText:Upton and his girlfriend Evelyn Zeller lived on a quiet street in Encinitas, California.
Zeller told "20/20" that the couple was peaceful and quiet and focused on helping others. Settled among the gentile hills, Lone Jack Road looked like the setting of any California dream.
But this quaint street would soon look more like a duel scene of a western film when two neighbors got into a dispute over landscaping.media:24697137
quicklist:2title:Michael Vilkintext:In 2008, 55-year old Michael Vilkin, an immigrant from former Soviet Georgia, bought the 2.6 acre lot that was adjacent to the house Upton was renting.
In order to develop the land, Vilkin needed to clear the brush, including the non-native, invasive and poisonous Brazilan pepper-trees.
He spent every spare moment working the land, nursing it back to health in hopes to build his dream home. But many of his neighbors thought Vilkin had become obsessed, working the land the old fashioned way with a shovel and wheel barrow even using a handsaw and axe to control acres of brush.
John Upton’s family said it irked him that Vilkin was unnecessarily removing trees, and ruining the privacy of his rental home.media:24697009
quicklist:3title:The Disputetext:For over a year the two neighbors disputed over clearing of the lot, focusing on a narrow 130-foot strip of the land that was right outside Upton’s front door.
Vilkin wanted to clear it of invasive non-native Brazilian pepper-trees. Upton didn’t want him to cut down the trees.
The strip became a battleground. According to Michael Vilkin, Upton would intimidate him, screaming and yelling at him to stop cutting trees, every time he was out working on his land.media:24696687
quicklist:4title:The Final Confrontation text:On March 28, 2013, the battle over the land came to a deadly end.
According to prosecutors, Upton went outside that morning and was shot down by Vilkin, with a .44 caliber Ruger gun.
Vilkin said he saw Upton coming towards him, yelling and swearing, and holding what he thought was a gun. Vilkin said that when Upton got too close, Vilkin shot him in self-defense. The “gun” Vilkin thought he saw in Upton’s hand was in fact, a BlackBerry.media:24696518
quicklist:5title:Michael Vilkin's Arresttext:Vilkin is arrested and is held on a $5 million bail.
Both families are left struggling to understand what happened between the two neighbors.
Vilkin’s wife told ABC News' Matt Gutman, “Michael has a beautiful heart. I did not believe it. I still don’t believe it.”
Upton’s children also struggle to find a reason behind the altercation that left their father dead.
“It’s devastating,” Elizabeth Upton, John Upton’s adult daughter, told "20/20." “Who would do this? Who is this guy [who] murdered my father in cold blood? For what?” media:24696406
quicklist:6title:The Trial text:At his trial, Vilkin testified that he was acting out of self-defense, claiming on the stand that Upton had been verbally harassing him and he felt unsafe.
“I was afraid of John Upton,” Vilkin testified. “I was afraid he would do something dangerous.” media:24696016
quicklist:7title:The Guntext:Vilkin shot Upton twice: once in the abdomen, and then, several seconds later, in the head.
He testified in court he thought he saw a gun in Upton’s hand.
“When he was about ten feet away, I saw a pistol in his right hand,” Vilkin said on the stand. “I pulled out my revolver and shot him, but he made a couple more steps. I screamed, ‘Stop!’ recocked and shot him in the head."
But investigators didn't find any evidence that Upton was carrying a gun. They only found Upton’s Blackberry at the scene.
A jury deliberated for three days and found him guilty of murder in the first degree and assault with a deadly weapon. He could face 50 years to life in prison when he is sentenced in August 2014. media:24696271
quicklist:8title:Jailhouse Interviewtext:Even from jail, Vilkin is unapologetic about his actions.
In an exclusive jailhouse interview with ABC News' Matt Gutman, Vilkin said he would not hesitate to act if he felt threatened.
“I’m not [the] kind of person who, if you spit in my face, [will] just turn around and leave,” Vilkin said.media:24696171