A convicted killer got a second life sentence Thursday after he was found guilty of a 2005 execution-style murder, court officials said.

Ronald Fisher was already serving life in prison for a 2011 murder conviction when he was charged with fatally shooting 17-year-old Eddie Shaheed, authorities said.

Prosecutors said Shaheed was walking with friends along Cascade Avenue in southwest Atlanta on May 30, 2005 when they encountered Fisher and another group of young men.

A verbal dispute began between the two groups, but Shaheed turned to leave, prosecutors said.

When the teen’s back was turned, prosecutors said Fisher pulled a gun and shot Shaheed in the back of the head before firing at Shaheed’s friends, then fleeing.

No one else was hurt, and an arrest eventually was made of the wrong person, prosecutors said.

Those charges were later withdrawn and the case stayed cold until 2011, when new evidence identified Fisher as the gunman, authorities said.

He already was in prison for the 2011 conviction in a 2009 killing, authorities said.

Thursday, Fulton County Superior Court Judge Robert McBurney sentenced Fisher to a life term that will run consecutive to his first life sentence, officials said.