NEW ORLEANS — A lawyer for a white police officer who shot and killed a black man about three years ago after a foot chase argued Tuesday to an appeals court that his client should be protected by federal immunity. But state prosecutors disagreed, saying the case never should have been dismissed by a lower court.

The 5th Circuit Court of Appeals heard arguments in the case of Charles Kleinert, an Austin police officer working with an FBI task force investigating bank robberies when he encountered Larry Jackson Jr on July 26, 2013. Court records say Jackson tried to enter a bank that was closed, saying he wanted to make a withdrawal. Kleinert was inside, and bank employees who talked to Jackson told Kleinert he lied about his identity.

Kleinert went out to investigate and after a short conversation, Jackson ran off. Kleinert gave chase. When he caught up to Jackson, a struggle ensued and Jackson was shot in the back of the neck and died.

Kleinert’s team have argued that the shooting was the result of an accidental discharge and that Kleinert should be granted immunity, under a more than 100-year-old court ruling protecting federal officers from state prosecution if they were carrying out their duties in a reasonable and proper manner. The protection doesn’t shield all acts by federal law enforcement, but it does create a different, and what many consider a more forgiving, standard for their conduct than state law.

Prosecutors said he acted recklessly, used excessive force, and that at the moment Jackson ran, Kleinert had no reason under federal law to chase him so he couldn’t have been acting in his capacity as a federal officer and thus not entitled to the immunity.

A Texas grand jury indicted Kleinert for manslaughter in May 2014. Before the case went to trial, a federal judge dismissed it, citing the immunity clause. The state appealed to the 5th Circuit.

In front of a three-judge panel Tuesday, Kleinert’s lawyer, Randy T. Leavitt argued that it was clear that Kleinert was acting as a federal officer and thus should be protected by the immunity ruling.

“He went back to the bank as a task force officer,” Leavitt said, noting that Kleinert was there to pick up a surveillance video as part of an investigation into the bank’s robbery.

But Travis County assistant district attorney Rosa Theofanis called on the judges to overturn the lower court’s verdict.

“The district court erred in dismissing the case,” said Theofanis, suggesting it had gone out of its purview to decide facts of the case that were still in dispute. She also challenged whether the case should have ever been moved from state court to federal court.

At one point, Judge Jennifer Walker Elrod questioned whether Kleinert’s striking of Jackson was “reasonable” and raised questions about how the point-blank shot to the back of Jackson’s head could have happened.

That sparked one of the hearing’s most interesting moments in which Leavitt re-enacted the shooting, describing how Kleinert grabbed Jackson’s shirt and then when Jackson turned, both fell together.

“He didn’t know whether this fleeing fellow was armed or not,” Leavitt said. “They trip and fall and as he does, the gun discharges.”

The hearing comes at a time of intense focus across the country on police treatment of minority suspects with many in the black community demanding more oversight and prosecutions of police killings.

Follow Santana on Twitter at