It's the Sig Sauer P239, the model of a semi-automatic handgun at the heart of the trial of Jose Ines Garcia Zarate, who was found not guilty Thursday in the 2015 death of Kate Steinle.
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On the last day of the jury's deliberation, San Francisco Public Defender Jeff Adachi said the jury asked to pull the trigger on the unloaded weapon, but the judge refused.
"I think it was an incorrect decision by the judge," said former Alameda County Deputy District Attorney John Creighton, who told ABC7 News he believes, had jurors been able to try to pull the trigger, the verdict might have been different.
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"The issue here is so central to what took place," he said. "The jurors should have been allowed to do it."
The federal ranger whose gun was stolen testified he left it in double-action mode, which requires two actions before a handgun will fire. It's unclear whether it was still that way when Garcia Zarate fired the fatal shot.
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Either way, gun expert Roman Kaplan said pulling the trigger on the Sig Sauer P239 takes more pressure than many other guns. The pressure required is from 6 to 10 pounds, he said, demonstrating at his Pleasant Hill store, City Arms East.
"Without being hands-on, with such a key piece of evidence... and make a decision that probably the gun go off by itself, I think it was a mistake," he said.
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But Hastings College of the Law Professor David Levine said, since it was the defense and not the prosecution that asked for jurors to handle the gun, the judge's ruling probably was not a major factor.
"It was a matter of discretion by the judge," explained Levine. "In this case, while people are understandably questioning what happened, it's what we would call harmless error, because it did not affect the result of the case."
The law is clear on one issue. As a convicted felon, Garcia Zarate should never have been in possession of any gun, even for an instant.
TIMELINE: How the Kate Steinle case unfolded
Click here to look back at the events of the Kate Steinle murder trial.