"They appeared to be circling the seat looking down, bending down," Ugarte said. "We believe that it's entirely likely that group of individuals discarded the weapon."
Grainy surveillance video from a pier over a quarter-mile away captured the July 1, 2015, shooting, and footage from an hour before, when six figures appeared to convene around the steel seat for almost 30 minutes. Members of the group appeared to repeatedly bend down around the base of the chair, setting down and then picking up blurry objects.
They left the pier at approximately 5:38 p.m., and Garcia Zarate arrived at the seat about 6:07 p.m.
The evidence was entered during testimony from Paul Endo, an expert video analyst hired by the defense. Garcia Zarate is charged with murder, and the prosecution is arguing he likely brought the gun with him to the pier and intended to fire the shot that killed Steinle.
Ugarte said police didn't investigate the group who gathered at the scene, and they missed an opportunity to corroborate Garcia Zarate's story.
"You would imagine that sergeants -- experienced homicide inspectors -- looking at surveillance footage would want to know how that gun got to the pier," Ugarte said, "particularly when Mr. Garcia Zarate said he found it there, particularly when there is a meeting of six individuals on the pier half an hour before he sits down. They didn't investigate it. It's unclear why. It's sloppy. And unfortunately, we're the ones putting forth that evidence."
During cross-examination Wednesday morning, prosecutor Diana Garcia asked Endo whether he could tell if the group gathered around the steel seat was engaged in criminal activity. Endo said he couldn't tell.
Garcia noted that the group appeared to gather around the chair for 28 minutes. She asked Endo if a group doing something criminal would "hang out for 28 minutes."
"I don't know what a criminal group would do," Endo said.
Garcia asked him if he was told the defense's theory of the case -- that Garcia Zarate didn't mean to fire the shot that killed Steinle -- and essentially find evidence to support it. Endo said he was asked to enhance the video and point out anything unusual, especially at the metal seat.
"Are you aware that they're trying to show, through you, that they were dropping the gun there?" Garcia asked.
Endo said he was hired by the defense to analyze the video but didn't initially know about the defense argument.
During direct testimony Tuesday, Endo also discussed video from the seconds before the shooting at approximately 6:30 p.m. He said the extremely blurry magnification of Garcia Zarate showed him move his leg and then bend down just before Steinle fell. She was standing next to her father, James Steinle, who can be seen on the video moving to help her.
Garcia Zarate's movements, however, were not clearly visible until he got up to leave after the shooting.
"Is it your testimony that the blob that we saw yesterday is a clear image?" Garcia asked Endo on Wednesday about the zoomed-in portion of the surveillance video of Garcia Zarate's position moments before Steinle fell.