A Cobb County man was sentenced to 20 years in prison Friday morning after being convicted in a 2013 Christmas Day shooting, the district attorney said.

Tadarius Cornelius Williams, 19, was convicted of aggravated assault and aggravated battery for shooting Jermarcus Thompson twice outside an Austell Road apartment after an altercation with a girl, DA Vic Reynolds’ office said. Thompson was seriously injured and has undergone multiple surgeries, Reynolds said.

Although Williams claimed he was nowhere near the crime scene, he was heard on a Cobb County jail phone telling a friend that he was “going away for some years,” after his April arrest, according to prosecutors. A fellow inmate testified that he and Williams had discussed executing potential witnesses.

“What innocent person – someone who wasn’t anywhere near the scene, as he claims – is resigned to going to prison for years?” Assistant DA Courtney M. Veal said during closing arguments. “Who talks about killing witnesses if they’re innocent?”

Investigators also had evidence that Williams, who goes by the street name “Grits,” was involved in a gang, Reynolds said.

Williams had been held at the Cobb jail without bond since his April 2 arrest. Judge Reuben Green sentenced him to serve 20 years in prison.