LOS ANGELES—A former barber was sentenced Wednesday to life in prison for murdering a mentally ill homeless man by splashing him with gasoline and setting him ablaze to settle a grudge.

Ben Matthew Martin, 31, pleaded guilty last month to the 2008 murder of John McGraham.

The attack horrified the central Los Angeles neighborhood where McGraham had lived on a sidewalk for years, befriending many residents.

Martin, a slightly built, bespectacled man with a shaved head, sat with his head bowed during the sentencing hearing, where several of McGraham's family members and friends spoke emotionally about the victim and the way he died.

"I only wish Ben had some compassion for John," McGraham's younger sister Susanne McGraham-Paisley said through tears. "He must have seen him as a filthy heap of a bum who deserved not to live. (John) was good, kind and thoughtful. He never hurt anybody."

Supporters displayed a large photo of a younger McGraham. Several wore "Justice for John" T-shirts.

McGraham-Paisley said she had been taking her children to visit her brother on the street since they were toddlers to teach them not to be ashamed of their uncle and to have compassion.

She said Martin had been fired from a neighborhood barber shop after harassing McGraham on the street. Several months later, Martin sought revenge with a can of gasoline and a road flare. People rushed to aid McGraham as he was engulfed in flames, but it was too late.

"I have wondered so many times what was going through my brother's mind," said McGraham-Paisley, who runs a legal services business. "I was told he lifted his hand in some kind of acceptance of what was to come."

She told The Associated Press that Martin was obsessed with cleanliness and was surprised people condemned him for killing a homeless man.

"From his warped point of view, he thought he was cleaning out the neighborhood," she said.

Her brother David McGraham choked up as he spoke in the courtroom.

"This whole thing is so terribly tragic," he said. "If (Martin) could've seen that deep down they shared the same humanity."

McGraham-Paisley said she did not hate Martin but viewed him as another type of victim. Martin's mother had tried to help her son with his emotional turmoil, but he had refused assistance -- just like her brother, McGraham-Paisley said.

Still, McGraham-Paisley was gratified that Martin would pay for his crime for the rest of his life and not be free to harm others.

She said she consoles herself with the thought that her brother did not die in vain.

"I think there are a lot of people who as a result of this crime take a different look at the homeless," she said.

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