Garcia-Zarate’s defense attorneys argued that the shooting was unintentional, that he found the gun wrapped in a cloth under his seat at the pier and that it accidentally discharged. The bullet ricocheted off of the ground and struck Steinle in the back as she was walking, 78 feet away, with her father.

The 1st District Court of Appeals ruled Friday that the trial judge made a “prejudicial” error when he failed to give the jury “the momentary possession instruction.”

“It is undisputed that defendant was holding the gun when it fired. But that fact alone does not establish he possessed the gun for more than a moment. To possess the gun, defendant had to know he was holding it,” the appellate court wrote.