Kentucky State Police say the conflict began a month ago in a Sam's Club parking lot in Lexington.
One man, a doctor with a highly visible practice off Richmond Road, accused a Clark County man of keying his Acura.
Their dispute had a fatal ending Sunday, when Dr. Rodney M. Mann, 45, was shot and killed with his own gun in the driveway of Charles B. Steppe's home in rural Clark County.
Police said Mann, allegedly armed with a knife and two handguns, parked his car a quarter-mile away from Steppe's home on Four Mile Road. Steppe told police that about 11 a.m., he heard the sound of air escaping the tires of his vehicle, which was parked in his driveway. He would later tell state police that he saw Mann slashing the tires.
Police said Steppe went outside and confronted Mann, who allegedly was holding the knife and a handgun. A second gun was tucked in his waistband, according to police.
Police said the two men struggled over the gun, Steppe wrestled it away and then Mann came at him with a knife. Steppe fired several rounds. One bullet hit a major artery in Mann's leg, and he bled to death in the driveway, according to an autopsy performed Monday.
Steppe called 911 and told the operator that he had shot someone, police said.
The Clark County Coroner's office pronounced Mann dead at the scene.
State police said they aren't sure what happened between the two men at Sam's Club on New Circle Road. But "that's where we think this little feud originated," Trooper Chris Lanham said.
Steppe has not been arrested, but officers will present the case, which is under investigation, to the Clark County grand jury, state police said.
"It's of the opinion of the investigators that it's a case of self-defense," Lanham said.
Mann was an immunologist at Thoroughbred Allergy and Asthma Center near Richmond Road, according to the center's Web site. A woman who answered the phone at the office said the center has closed for the week.
Mann's Facebook page says he is the chief executive of the center. It also says he is a graduate of the University of Kentucky and that he graduated from Knox Central High School in 1982.
He graduated from the University of Louisville School of Medicine in 1990, according to the Kentucky Board of Medical Licensure.
His Facebook profile includes several photographs of him wearing camouflage and holding guns.
He lists his favorite quote as: "This is a 44 magnum, the most powerful handgun in the world and could blow your head clean off. So you have to ask yourself one question ...do I feel lucky? Well, do ya ...Punk?"
Several of Mann's friends and family left messages on the wall of his Facebook page, expressing their sadness and well wishes.
Philip Burgert wrote: "Cousin Rodney, I'm so sorry to hear what happened. May peace find you on the other side. Thanks for being part of our family and life."