Austin’s progressive district attorney, José Garza, is pushing back against the governor of Texas, Greg Abbott, for his promise to pardon a former army sergeant, Daniel Perry, who on Friday was convicted of murder for killing a Black Lives Matter protester, Garrett Foster.

Mr. Abbott, alongside other conservative figures and Perry himself, has argued that Perry acted in self-defense when Foster approached Perry’s car with a gun after Perry drove into a crowd of BLM protesters. Whether Foster aimed his weapon at Perry was at the heart of the case and Perry’s defense was unable to prove in court that Foster did so.

“Texas has one of the strongest ‘Stand Your Ground’ laws of self-defense that cannot be nullified by a jury or a progressive District Attorney,” Mr. Abbott said.

The governor added in a statement Saturday that he would be working to secure a pardon for Perry, something that must first go through the Board of Pardons and Paroles in Texas.

“Texas law DOES allow the Governor to request the Board of Pardons and Paroles to determine if a person should be granted a pardon,” Mr. Abbott wrote. “I have made that request and instructed the Board to expedite its review.”

Mr. Abbott added that he is also prioritizing “reining in rogue District Attorneys, and the Texas Legislature is working on laws to achieve that goal.”

In response, Mr. Garza accused the governor of interfering with the legal process in Austin and argued that the jury had reached the correct verdict.

“In a state that believes in upholding the importance of the rule of law, the Governor’s statement that he will intervene in the legal proceedings surrounding the death of Garrett Foster is deeply troubling,” Mr. Garza said.

Mr. Abbott’s social media announcement came less than 24 hours after Perry was convicted for the July 15, 2020, murder of Garrett Foster. Perry was not convicted on a related charge of aggravated assault.

While Perry’s lawyers argued that Perry acted in self-defense, prosecutors successfully argued that Perry had instigated the incident that led to Foster’s death.

“After hearing from civilian eyewitnesses and expert witnesses, and deliberating for over 15 hours, they reached the unanimous decision that Daniel Perry did not kill Garrett Foster in self-defense and was guilty of murder beyond a reasonable doubt,” Mr. Garaza said.

On the night of the incident, Foster was part of a Black Lives Matter march at downtown Austin when Perry, who was driving an Uber at the time, ran a red light and drove into a crowd of protesters.

During the trial, the court heard that though Perry slowed down when he entered the crowd, he had previously discussed driving into a protest.

Perry had talked with a friend weeks before about an incident at Seattle where a driver killed multiple protesters by driving into the crowd. Perry said that the driver could and should claim self-defense, even if he incited the crowd.

After Perry entered the crowd on July 25, 2020, Foster approached the car with an assault weapon drawn. According to the Austin Police, Perry fired five shots into Foster, though Foster never fired his weapon. Another protester shot at Perry’s car three times as he fled the scene; no one was hit.

Mr. Garza is one of a group of progressive prosecutors who have come under criticism for receiving campaign funding from groups linked to a liberal billionaire, George Soros.

Mr. Garza’s election campaign received some $400,000 from the Texas Justice and Public Safety Political Action Committee, which in turn had received significant funding from Mr. Soros.

Mr. Abbott’s Saturday statement came after a Fox News host, Tucker Carlson, had criticized the governor for not stepping in to pardon Perry on his program.

“This case should have never been prosecuted. A pardon by the governor is in order,” Mr. Carlson said. “There is no right to self-defense in Texas.”

In response to Mr. Abbott’s promise to pardon Perry as soon as a resolution lands on his desk, Foster’s fiance, Whitney Mitchell, said the governor is depriving her of justice and relief.

“I felt some sense of justice and relief,” Ms. Mitchell said. “The governor has immediately taken that away since he announced there are two legal systems in Texas: One for those with power, like Mr. Perry, and one for everyone else.”