Murder case seized on by Trump to justify border wall opens with judge ruling out any mention of politics

The Mexican immigrant denies the charge of murder

The 32-year-old was shot and killed while walking with her father (Facebook)

The judge overseeing the trial of an illegal immigrant whose shooting of a young woman was seized on by Donald Trump during the presidential campaign, has ruled that the politics of immigration and gun control must not be raised during the hearing.

Defendant Jose Ines Garcia Zarate has acknowledged fatally shooting Kate Steinle in the back while she was walking with her father on a San Francisco pier in 2015. The 54-year-old claims he did so accidentally, after handling a weapon he found wrapped in a T-shirt under a bench on the pier.

As opening statements were delivered on Monday, prosecutors dismissed Mr Zarate’s claim and insisted he had shot Ms Steinle intentionally.

Mr Zarate has pleaded not guilty (AP)

The Associated Press said Deputy District Attorney Diana Garcia showed the gun to the jury and said a ballistics expert would provide testimony that it could only be fired by pulling the trigger.

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

The shooting of 32-year-old Ms Steinle was pounced on by Mr Trump during the election campaign and he cited it as evidence of the need for a tougher approach to immigration. He called Mr Zarate “an animal” and said the incident underscored the need to build a wall on the US-Mexico border.

Two days after she was killed, Mr Trump said her death was “yet another example of why we must secure our border immediately”.

He added: “This is an absolutely disgraceful situation and I am the only one that can fix it. Nobody else has the guts to even talk about it. That won’t happen if I become president.”

Mr Zarate is charged with second-degree murder, which could result in a sentence of 15 years to life in prison if he is convicted. He has pleaded not guilty.

Ms Steinle’s mother and brother attended the opening of the trial.

The AP said Mr Zarate had been deported five times and was homeless in San Francisco when he shot Ms Steinle. He had recently completed a prison sentence for illegal re-entry to the US when he was transferred to the San Francisco County jail to face a 20-year-old marijuana charge, it added.

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

Mr Zarate lawyer, Matt Gonzalez, told reporters before the start of proceedings, his client was unaware that he had picked up a gun on the pier.

“He does not bear criminal responsibility,” said Mr Gonzalez.

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

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.