SAN FRANCISCO (AP) — A tourist visiting a popular San Francisco pier two years ago snapped three quick photographs that turned out to be key pieces of evidence in the high-profile murder trial of a homeless Mexican man charged with killing a woman two years ago.

The witness’ photographs captured Jose Ines Garcia Zarate sitting on a seat on the pier and the back of Kate Steinle several yards (meters) away moments before she was shot on July 1, 2015. They were displayed to the jury Tuesday during the second day of Garcia Zarate’s trial.

Steinle’s death sparked debate over immigration and so-called sanctuary city policies because the man charged with her murder was deported to Mexico five times before the shooting.

The witness, Michelle Lo, testified that as she walked onto the pier she noticed Garcia Zarate because he was spinning around in the chair, which was built to revolve. She did not look long at him but testified he made her feel uncomfortable.

Lo, who lawyers said lived on the East Coast but didn’t specify the city, testified with the aid of Cantonese interpreter.

“I did not pay special attention to him,” Lo said, adding that Garcia Zarate caught her eye because “the chair was spinning and I saw him.”

The handgun fired in the killing 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.

Garcia Zarate, 54, has acknowledged shooting Steinle in the back, but said the shooting was accidental and that he was handling the handgun when it accidentally fired.

He is charged with second-degree murder and faces a sentence of 15 years to life in prison if convicted.

Garcia Zarate was homeless in San Francisco when he shot Steinle. He had recently completed a prison sentence for illegal re-entry to the U.S. when he was transferred to the San Francisco County jail to face a 20-year-old marijuana charge.

Prosecutors dropped that charge, and the San Francisco sheriff released Garcia Zarate from jail despite a federal immigration request to detain him for at least two more days for deportation.

The sheriff’s department said it was following the city’s sanctuary policy of limited cooperation with federal immigration authorities.

President Donald Trump frequently cited the case to highlight problems with U.S. immigration policy during the presidential race last year.

Since being elected, Trump has threatened to withhold federal funding to so-called sanctuary cities such as San Francisco, several of which have filed lawsuits to prevent the move.

The judge has prohibited mention of the politics of immigration and gun control during the trial that is expected to last several weeks.

Garcia Zarate went by the name Juan Francisco Lopez-Sanchez when he was arrested. But Gonzalez said he now prefers to be called by his birth name of Garcia Zarate.