Updated

The Latest on the trial of a Mexican national charged with murder in the death of a woman on a San Francisco pier. (all times local):

5:45 p.m.

A veteran police inspector and shooting instructor testified Monday at a San Francisco murder trial at the center of an immigration debate that accidental gun discharges start with the shooter's finger on the trigger.

John Evans, who helped lead the investigation of Kate Steinle's 2015 shooting death, said handguns don't fire by themselves. Evans, who retired from the San Francisco police department last year, sparred with the lawyer representing Jose Ines Garcia Zarate, who is charged with murder for Steinle's death. Garcia Zarate's attorney, Matt Gonzalez, argues that the gun his client was handling while sitting on a San Francisco pier accidentally fired, striking Steinle in the back.

Gonzalez pointed out that between 2005 and 2011, San Francisco Police Department officers reported 29 accidental discharges of service weapons similar to the weapon used to kill Steinle. Evans countered that in most accidental discharge cases, the gun was handled improperly and fired with a finger on the trigger. The trial continues Tuesday.

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5:20 p.m.

A retired police officer says the bullet that killed a San Francisco woman whose death touched off a national debate about illegal immigration ricocheted off the ground about 100 feet away before hitting her in the back.

Former Officer John Evans said Monday he and other investigators working on the case found a "strike mark" on the pier's concrete surface four days after the shooting of Kate Steinle by a Mexican national who had been deported five times.

He said authorities found the bullet was partially flattened, indicating it had ricocheted.

Lawyers for defendant Jose Ines Garcia Zarate say the ricochet shows the shooting was accidental.

Prosecutors have charged Garcia Zarate with murder, alleging he intended to point and shoot the gun at pedestrians on the pier on July 1, 2015.

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This story has been corrected to say the bullet traveled 100 feet, not yards.