Did shooter toss gun in fright or to cover up crime?

San Francisco police Officer Scott Hurley of the department’s dive team had veered off course in his search of the bay floor south of Pier 14. With zero visibility, he had to feel his way back toward the correct course over large boulders and debris.

It was then, on July 2, 2015, that his hand slipped through a crevice between two rocks. “And my hand touched something that felt unique,” Hurley said Wednesday in San Francisco Superior Court.

That something was the stolen .40-caliber handgun that had, the previous evening, fired the single bullet that pierced Kate Steinle’s back as she strolled with her father along the pier.

As the trial into the fatal shooting that fueled a national debate about immigration and sanctuary laws went into its third day, the prosecution focused on the aftermath of the killing in its effort to prove that the defendant, 45-year-old Mexican citizen Jose Ines Garcia Zarate, had intentionally fired the gun toward Steinle and should be convicted of seconddegree murder.

The defense says the shooting was an accident, with the gun going off in Garcia Zarate’s hands after the homeless man with a history of deportations and drug crimes found it wrapped in a T-shirt or cloth under a bench.

Surveillance video — what has long been considered the 21st century version of a smoking gun in criminal cases — only further muddled the two conflicting narratives when the prosecution introduced the footage Wednesday.

In her opening statements, Assistant District Attorney Diana Garcia said Garcia Zarate’s actions reflected his guilty state of mind. Prosecution witnesses have since said he tossed the firearm into the bay and walked away as bystanders rushed to aid the wounded Steinle.

When Officer Andrew Bryant came across him about an hour after the shooting near the Java House on Pier 40, Garcia Zarate was “a deer in the headlights.”

“His eyes got really big and he stood up,” Bryant testified Wednesday. “He walked away in a fast pace.”

Garcia Zarate’s attorney, Matt Gonzalez of the public defender’s office, said in his opening statement that the evidence jurors will hear — including that the bullet skipped off the ground before hitting Steinle — supports an accidental discharge.

The defendant tossed the gun into the bay because he was frightened it had gone off, Gonzalez said, not because he was trying to cover up a crime.

A crime scene investigator also testified on Wednesday that he did not find any shell casings on the pier, which Gonzalez said supported the theory that the gun had been wrapped in a cloth when it fired.

And though Officer Hurley of the dive team said he did not find a cloth when he located the gun in the bay, Gonzalez raised the possibility that the cloth could have been buried or swept out into the bay. Under cross-examination, Hurley said he was not instructed to search for a shirt or cloth while underwater.

In the afternoon, Garcia played an enhanced version of the surveillance video taken from a camera a quarter of a mile away on the firehouse pier. Even zoomed in, the video only showed a black figure, identified as Garcia Zarate, and a white spot, identified as Steinle, walking away from the black figure and then falling to the ground.

The footage showed the figure identified as Garcia Zarate almost immediately tossing the gun into the bay and leaving the scene, slowly meandering down the Embarcadero and looking into garbage cans before encountering Officer Bryant near Pier 40.

The pistol had been stolen from a U.S. Bureau of Land Management ranger’s car four days before the shooting, when the off-duty ranger drove into the city and parked along the Embarcadero. No one has been arrested in the burglary.

Before the shooting, Garcia Zarate had been on track for a sixth deportation after serving 46 months in prison for felony reentry into the country. But he was transferred from federal custody to County Jail in March 2015 on an old warrant alleging he fled marijuana charges in 1995.

When city prosecutors discharged the case, the Sheriff ’s Department, relying on the city’s sanctuary policies, released Garcia Zarate despite a federal request to hold him for deportation.

The case sparked a push against the policies, and the House of Representatives in June passed “Kate’s Law,” which would boost punishment for people who repeatedly enter the U.S. illegally.

San Francisco has stood by its sanctuary laws, with officials saying they benefit public safety by ensuring that immigrants, including witnesses to crimes, feel comfortable working with authorities.