A Criminal Court jury on Friday morning ruled Derrick Blake Summers guilty of voluntary manslaughter in the Sept. 30, 2000, shooting of 42-year-old James Edward Gurley.
Summers, 22, faces a sentencing range of three to six years. Judge Doug Meyer will set the sentence on March 8.
The state had been seeking a first-degree murder conviction, which carries life in prison.
Summers remains free on a $50,000 bond as the case is appealed.
The jury had deliberated four and a half hours on Thursday afternoon, then another 40 minutes on Friday morning.
The defense are argued it was a case of self-defense.
Gurley died 42 days after being shot in the chest at the corner of Orchard Knob Avenue and 14th Street.
Prosecutor Rodney Strong told the jury that the pair had a confrontation earlier in the day.
He said Summers "was still mad at him about the earlier incident" when they ran into each other just after midnight.
The prosecutor said Gurley had gone out to buy cocaine and Summers had made a disparaging remark about his girlfriend, Cynthia Beard. He said Gurley pulled a knife, but that Harold Jackson Sr. had intervened.
Defense attorney Jeffery Schaarschmidt said Summers "knew that Gurley had a propensity for violence."
He said Summers took a roundabout way to visit his girlfriend and baby on his bicycle, but still ran into Gurley and Ms. Beard.
He said Gurley swung a stick at Summers and that Summers fired as Gurley swung at him a second time.
The attorney said if Summers had wanted to kill Gurley he could have pumped numerous shots into him as he lay on the street after Summers had returned to retrieve his weapon.
He said that Summers ran home and "cried his eyes out for over two hours."
Ms. Beard testified that Summers had made an ugly remark toward her when they had gone out to buy drugs. She told of Jackson intervening after Gurley pulled the knife. She said Gurley was already mad because someone had run off with some money he had intended to use to buy crack cocaine.
She said they were on foot headed to a Conoco to buy beer when they ran into Summers. She said Summers fired a shot as Gurley swung the stick.
She said Summers said, "I told you I was going to get you."
Ms. Beard said she went into Arcade Printing to get help and when she came back she saw Summers going back to get the gun.
Ms. Beard was in workhouse garb because she is serving a term for burglary and theft. She said she has three prior cases of prostitution as well as theft, passing worthless checks and other charges.
The jury was sequestered.