NEW ORLEANS — A man convicted in a 2014 gunfight that left one bystander dead and nine people wounded on tourist-filled Bourbon Street won a partial legal victory Wednesday when a state appeal court vacated his manslaughter verdict, in effect reducing it to negligent homicide and cutting his 60-year prison sentence to no more than 25.

Trung Le, 24, remains convicted of attempted manslaughter in the case and his maximum 20-year sentence for that crime stands. But the state 4th Circuit Court of Appeal said the manslaughter conviction and maximum 40-year sentence for the death of nursing student Brittany Thomas cannot stand because the bullet that killed Thomas was fired by another man — the one who exchanged gunfire with Le and has never been found or identified.

The appellate court sent the case back to state Judge Byron Williams for re-sentencing on the negligent homicide charge, which carries a maximum five-year sentence.

"Under Louisiana law and jurisprudence, the defendant's manslaughter conviction for the death of Ms. Thomas cannot be upheld because he did not physically kill her and was not acting in concert with her actual killer, the unknown male," Wednesday's ruling said.

The three-judge panel rejected Le's lawyers' contention that the attempted manslaughter charge also was incorrect. Le's defense had been largely based on the claim that he was trying to protect himself and others when he opened fire on the unknown second gunman, who returned fire according to prosecutors. Evidence in the case was sufficient to find that Le's use of force had not been necessary, the ruling said.

District Attorney Leon Cannizzaro said he disagrees with the reduction of the manslaughter conviction and will appeal to Louisiana's Supreme Court.

The shooting that killed Thomas, a nursing student from Hammond, Louisiana, happened early on the morning of June 29, 2014, on the famous street of tourist-friendly nightspots in the heart of New Orleans' historic French Quarter. Others hit by the gunfire included visitors from Australia, Mississippi, Alabama, Arkansas and Florida, some of whom testified about the lingering effects of their injuries at Le's trial.

"I wish that I could sentence you to more," Williams told Le as he ordered him to serve 40 years on the manslaughter charge, followed by 20 more years for the attempted manslaughter conviction. Williams said Le had "dodged the proverbial bullet" when a jury found him guilty of manslaughter. He had been charged with second-degree murder, which carries a mandatory life sentence.