An Atlanta man has been sentenced for killing a man in a fight over smoking in home. He was charged with murder twice in the span of two years has been found guilty of a lesser crime in the first case, announced the Fulton County officials on Friday.

21-year-old Dontavis Montgomery, has stabbed Nicholas Roberts in the back during a fistfight in the January 2015, as per the news release from the district attorney’s office. He was found guilty of the charges including involuntary manslaughter and also aggravated assault.

The violent fight broke out after Montgomery’s half-brother has started smoking a cigarette in the Roberts southwest Atlanta living room, Roberts had asked Montgomery not to smoke in the room because his 11-year-old daughter has asthma.

Roberts wife and also her friend tried to stop the fight, but Montgomery has grabbed a kitchen knife and then he punctured Roberts lung, said the news release.

After fleeing from the scene, Montgomery has turned himself to the police six days later, claiming that he had stabbed Roberts in the defense of others.

He was released on the bond of $100,000 in October 2015. A year later, he was arrested and also charged in the murder of his cousin, Marquez Montgomery, aged 15.

Dontavis Montgomery said that the shooting was an accident. The case is still in pending.

In the case of Roberts death, Judge Todd Markel has sentenced the defendant to 20 years in the prison. Dontavis Montgomery attorneys did not answer to the call on Friday afternoon.

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Mrudula Duddempudi.