A Fulton County Superior Court jury couldn’t decide if an Atlanta man accused of fatally shooting an Iraq war veteran three years ago during a traffic argument was guilty.

The case against 27-year-old Charles Anthony Key ended Tuesday in a mistrial.

“They’ve been deadlocked the whole time,” said Fulton County assistant District Attorney Eleanor Ross. The trial began Wednesday and the jury deliberated for three days.

Key is accused of shooting Jack Snook, 24, in 2005 as the two drivers engaged in an argument at a Midtown red light. While a defense attorney characterized Key’s actions as self-defense from road rage, prosecutors sought involuntary manslaughter and aggravated assault against the father of two.

If convicted, Key could have been sentenced to 20 years in prison. Snook, a U.S. Marine, had returned from duty in Iraq three months before the shooting.

“We’re obviously disappointed,” said Snook’s grandfather Bob Hausleiter, who was on hand Tuesday with other family members for the verdict. “We’re heartbroken. There’s a child left without a father, and a wife left without a husband.”

Fulton District Attorney Paul Howard said, based upon conversations with Snook’s family and with jurors following the case, he would re-evaluate the office’s strategy and decide whether to retry the case.

“We have a strong feeling in our office that people should not take the law into their own hands,” he said. “It’s dangerous enough with the traffic in Atlanta.”

Key’s attorney, Dennis Scheib, said he wasn’t surprised by the outcome. “I didn’t think they’d find him guilty,” Scheib said. “The DA didn’t prove their case.”

On the two counts Key faced, the jurors voted 9-3 that he was not guilty for the involuntary manslaughter charge, and were split 6-6 over the aggravated assault charge, court officials said.

“It’s a situation that’s bad for everybody,” Scheib said. “My client’s done something he’s got to live with forever. [Snook’s] family loses a father and a son.

“I’m hoping everybody realizes this road rage situation has gotten way out of control.”