NASHVILLE, Tenn. (WKRN) — Metro police are trying to determine whether a 22-year-old woman acted in self-defense when she allegedly shot and killed a 38-year-old man in the parking lot of the Walmart on Lebanon Pike in Hermitage Saturday, following an apparent “road-rage” incident.

Authorities said Tristan Walker was driving with his girlfriend when the incident happened. Walker’s girlfriend told officers the 22-year-old woman was tailgating them. However, the woman said Walker brake-checked her, causing her to do the same to him in return.

According to officials, both vehicles entered from Andrew Jackson Parkway and stopped in the Walmart parking lot.

Walker then reportedly got out of his vehicle and approached the woman’s vehicle, causing her to fire one shot, hitting Walker in the chest.

Walker died at the scene, and police have not yet filed charges against the 22-year-old woman.

“It’s a messy case; that’s just my first impression,” said Ben Powers, a criminal defense attorney.

Powers told News 2 the back-and-forth alleged aggressive driving between Walker and the 22-year-old before the shooting further complicates the case.

However, he said there are certain conditions that must be met in order to claim self-defense under the law.

First, there must be a reasonable fear of imminent death or great bodily injury, according to Powers.

Next, there must be a true belief the threat of imminent harm or death is real.

Finally, that belief must be supported by the facts of the situation.

“The manner that he approached, what was he saying as he approached; what was she saying to him as he approached,” Powers said. “These are all the facts that go into the reasonableness or fear that you are in imminent harm, or you are in threat of imminent harm.”

If the above criteria is met, the law does not require a person to attempt to retreat, or leave a location before defending themselves.

“In Tennessee, you’re able to use deadly force even if the other person is unarmed, and in this case, even if you’re in your own vehicle,” Powers said. “There was no requirement that she turn her car back on, back out of the space, and drive off.”

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Homicide detectives will present the case to the District Attorney’s Office, which will have the final say on whether charges should be filed.

District Attorney Glenn Funk declined to comment on the case.