Dorian Harris, 17, grabbed a few cans of Spiked Watermelon beer from a cooler in the Top Stop Shop in Memphis last year. He ran out the door without paying, dropping one in his haste. The store clerk grabbed a handgun and chased him, firing off a few shots into the dark night, on March 29, the authorities said.

“I think I shot him,” the clerk, Anwar Ghazali, 29, told a customer when he returned to the store, according to a police affidavit and the Shelby County District Attorney’s office.

Mr. Ghazali didn’t call the police, the authorities said.

Mr. Harris’s body was discovered two days later in a nearby yard, where he had bled to death from a gunshot wound in the back of his left leg, the district attorney’s office said, and Mr. Ghazali was arrested.

After a four-day trial, Mr. Ghazali was convicted by a jury on Thursday of second-degree murder, the Shelby County district attorney, Amy Weirich, said in a statement on Friday.