Testifying before a packed courtroom, Jim Steinle was forced to relive the worst day of his life when he recalled the final moments of his daughter’s life as they took a summer’s evening stroll on a San Francisco pier more than two years ago.

Steinle told the court that he and a family friend were visiting his daughter Kate Steinle in San Francisco on July 1, 2015. After a late lunch at her favorite restaurant, the three decided to go for a walk on a pier on San Francisco’s popular waterfront.

Steinle said he soon heard a loud “bang,” before his daughter collapsed into his arms, pleading, “Help me, Dad.”

When she fell to the ground, her eyes were closed and she had difficulty breathing, he recalled.

“I couldn’t figure out what was wrong,” he said through his tears. “She didn’t have any health problems.”

He rolled his daughter on her side, lifted her blouse and discovered a bullet hole with little blood. Paramedics arrived on the scene and transported Kate to a nearby hospital, where she was declared dead.

The innocent woman’s death sparked a contentious debate on illegal immigration and so-called sanctuary cities after it became known that her murderer, Jose Ines Garcia Zarate, 54, was an illegal alien who had already been deported five times. He was homeless in San Francisco when he shot Steinle.

Zarate had recently completed a prison sentence for illegal re-entry to the U.S. when he was transferred to the San Francisco to face a 20-year-old marijuana charge. He is now charged with second-degree murder, which could result in a sentence of 15 years to life in prison if convicted.

Garcia Zarate’s trial began on Monday. Deputy District Attorney Diana Garcia showed jurors the handgun that he is accused of firing and said a ballistics expert will testify that the only way to fire it is to pull the trigger.

“It’s a very reliable, high-quality gun,” Garcia noted. “It’s one that won’t go off on accident.”

The defendant’s lawyer, Matt Gonzalez, claims that his client did not know he had picked up a gun when he reached under a bench and found something wrapped in a T-shirt. The lawyer says the gun had no safety and operated on a hair-trigger motion.

Claiming it was just an accident, Gonzalez rhetorically asked jurors if they believed prosecutors would have charged a “college student or Swedish tourist” with murder if they were the suspects instead of an illegal Mexican alien.

During last year’s presidential race, then-candidate Donald Trump pointed to the killing of 32-year-old Kate Steinle as a reason to crack down on U.S. immigration policies.

The handgun belonged to a U.S. Bureau of Land Management ranger who reported that it had been stolen from his parked car in San Francisco a week before Steinle was shot.