San Francisco (CNN) Her killing spurred congressional legislation aimed against illegal immigration, but the memory of Kate Steinle's brutal death was all it took to bring a San Francisco courtroom to a standstill Monday as her father struggled to tell what happened when she was struck down by a sudden bullet.

His voice breaking at times -- and with the man charged in his 32-year-old daughter's death sitting a few feet away -- James Steinle said he didn't know and couldn't tell that his daughter had been shot when she collapsed in front on him on a San Francisco pier in July 2015.

A passer-by, Steinle said, suggested that they turn her over. They did.

"You could see the bullet hole," her father said.

Prosecutors say Jose Ines Garcia Zarate, 54, an undocumented Mexican immigrant accused of repeatedly entering the United States illegally, fatally shot Steinle with a Sig Sauer .40-caliber handgun as she and her father walked on San Francisco' Pier 14. He is charged with second-degree murder.

Steinle testified Monday about those final moments. Earlier, attorneys delivered opening statements, with a prosecutor holding up the alleged murder weapon.

"He meant to kill Kate Steinle," Diana Garcia, an assistant district attorney in San Francisco told the jury. She described Garcia Zarate as a man who "intentionally" opened fire on people on the pier, killing Steinle, who sold medical equipment.

But defense attorney Matt Gonzalez said the shooting resulted from a "freakish ricochet."

"The gun was pointed at the ground when it discharged," Gonzalez said. "Had it been a public park, the bullet would have been embedded in the soil."

There has "never been a ricochet charge in history," Gonzalez added.

Garcia Zarate, who has pleaded not guilty, was formerly known as Juan Francisco Lopez-Sanchez, one of several aliases. CNN and other media outlets previously identified him as Juan Francisco Lopez-Sanchez.

The case has stirred controversy over immigration policy. Garcia Zarate was a convicted felon who'd been deported from the United States five times . Also, before the shooting, officials in San Francisco, a so-called sanctuary city, had released him instead of turning him over to immigration authorities.

JUST WATCHED Did sanctuary city policy lead to San Francisco murder? Replay More Videos ... MUST WATCH Did sanctuary city policy lead to San Francisco murder? 02:20

The Garcia Zarate case has also become a rallying cry for President Donald Trump and others, who have invoked Steinle's name in decrying sanctuary cities and promoting the construction of a border wall.

'Dad, help me. Help me'

Opening statements Monday focused mostly on the killing.

James Steinle, his daughter and a friend were "just strolling like regular tourists" on that July evening, around 6:23 p.m., the prosecutor said.

Garcia Zarate was seated when the three passed him, prosecutor Garcia said. Steinle took a selfie right before shots rang out about seven minutes after the group met up at the pier, the prosecutor said.

"Kate fell and her dad fell with her," the prosecutor told the jury.

Steinle's last words were: "Dad, help me. Help me," according to the prosecutor.

The bullet pierced the San Francisco woman's lower back and tore through her abdominal aorta, authorities said.

Attorneys deliver opening statements in the second-degree trial of Jose Ines Garcia Zarate.

Two women in a hotel across the street heard the gunshot and saw a man, who was "the only one rushing off the pier," according to Garcia.

Surveillance video captured Garcia Zarate running away, the prosecutor said. Another witness heard "a loud plop," the sound of the gun hitting the water, according to prosecutor Garcia.

"You'll see a splash in the water when the defendant throws the gun," Garcia said of the surveillance, adding that a police dive team recovered the weapon.

Garcia Zarate, who was arrested a mile away, eventually "admitted to deliberately firing the gun," after an interrogation that lasted more than four hours, the prosecutor said.

Investigators found gunshot residue on his right hand, according to Garcia.

The prosecutor said the Sig Sauer is "not the kind of gun to go off by accident."

Jose Ines Garcia Zarate listens to testimony during his second-degree murder trial.

'Emotional reaction shouldn't compound tragedy'

Authorities said the gun used in the shooting had been stolen from the car of an off-duty Bureau of Land management agent.

Defense attorney Gonzalez argued that Garcia Zarate found the gun at the pier, and accidentally discharged the weapon when he unwrapped it from a t-shirt.

The gun's "trigger pull is fairly light. It could accidentally discharge," Gonzalez said.

The defense attorney said an accidental discharge is "not a shock to people who know this gun."

"An emotional reaction shouldn't compound this tragedy," Gonzalez said.

He added: "An accident doesn't become something other than an accident because we don't like the results from it."

If the shooting "was purposeful," he said, Garcia Zarate would have fired more than once.

Garcia Zarate sat calmly in court as he listened to testimony from a Spanish translator on his earphones.

Gonzalez said Garcia Zarate has only a second-grade education, and he first came to the United States as a 14-year-old. The defense attorney argued that his client's background may have played a role in his prosecution.

"If this was a college student or Swedish kid would he be charged with murder?" Gonzalez said.

Testimony continues Tuesday.