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Jury to mull whether killing of Pomona officer was self-defense

After five weeks of contentious testimony, a jury will soon decide whether a Mongols Motorcycle Club member murdered a Pomona SWAT officer after he burst into his San Gabriel home nearly five years ago, or acted in self-defense because he didn't know the intruder was a police officer. 

David Martinez, 41, has been charged with murder and assault on a police officer with a firearm in the shooting that killed Shaun Diamond, 45, on Oct. 28, 2014. Martinez’s father, Arturo was also injured. 

Closing arguments begin Thursday at 9 a.m. in the Clara Shortridge Foltz Criminal Justice Center in downtown Los Angeles, after which the jury of six women and six men will begin deliberations. The trial began May 6. 

The prosecution, led by Los Angeles County Deputy Dist. Attys. Michael Blake and Jacques Garden, said that Martinez was a full-fledged, a.k.a. "full-patch" Mongol who knew officers were at his door at 4 a.m. when he fired his shotgun and then lied to cover up what he had done.

The defense, led by Public Defender Brady Sullivan, called the shooting "a perfect storm" of events that led to Diamond's death — "tragic, sad, unfortunate, but accidental."

Martinez, a clean-shaven man who worked as a termite inspector before his arrest, has a large Mongols tattoo on his chest, he acknowledged during the trial, but it wasn't visible under the conservative button-down shirts and dark ties he wore in court. 

He was visibly nervous when he took the stand on June 4. 

"I've never testified in court before," he said, "Never." 

Martinez’s voice broke as he began his description of the shooting. He said that he and his family, including his common-law wife and baby, his 10-year-old son and his parents, along with his sister who has Down syndrome, all share the small home. 

Martinez, who testified for two days, said he woke at 4 a.m. to hear a loud banging coming from the front of his house, where his parents and sister slept. 

With their four dogs barking and "that intense banging, banging," he said he grabbed a shotgun from under his bed and ran to the front room where he saw his father opening the front door and the tip of what appeared to be a gun pointing inside. 

Martinez said he told his parents not to open the door. He had argued with a Mongols member the night before, had unpaid dues to the organization and feared they were coming to hurt him. 

"I never heard anybody identify themselves as police," he said. "I remember telling my Dad twice, 'Wait, wait,' but I don't think he heard me ... I saw the screen door open up and I just remember seeing a barrel, a black barrel, and I fired the shotgun."

After that, he said he heard screaming coming from the porch and his father screaming, “Police!” His father had been shot in the arm, and Martinez said he threw down his gun and laid on the floor shouting, “I’m sorry, I’m sorry. I didn’t know you were the police. I thought you were the Mongols.” 

Diamond was shot in the back of the neck. Investigators believe he had turned away from the door to let his fellow officers move inside when he was struck.

Martinez said he didn't know until later — when he was handcuffed and sitting outside —that anyone other than his father had been shot. 

Later, under cross-examination, Blake asked Martinez: "You shot to kill that day?"

"I shot to protect my family," Martinez replied.

Martinez's parents believe the police had fired the shots that killed Diamond and grazed Martinez's father. Investigators say the only shot fired that morning came from Martinez's gun. 

Despite the chaos, none of the officers fired their weapons, the prosecutors said. They remained professional, they said, and did their jobs. 

Martinez's parents weren't allowed in the courtroom until after he testified, but his adult brother and sisters were always in the gallery, staying after court each day to pick up his laundry and make sure he had fresh clothes for the following day. 

Diamond's friends and family appeared daily as well, and at least a dozen of his law enforcement colleagues filled the courtroom the day Martinez took the stand. 

Diamond's daughter, Margo, said one day after the trial that her father, known for his sense of humor, was also an efficient and meticulous person.

"He always had a plan," Margo Diamond said. "He always had a way out." 

Diamond loved his SWAT duties, she said, but she never worried about that. She worried more about him riding his motorcycle to work than she did about him getting hurt on the job. 

The morning of the shooting, about 14 officers were at the house serving a search warrant as part of a multiagency operation targeting members of the Mongols Motorcycle Club. 

Martinez got involved with the Mongols in 2011, Sullivan said, but after a couple of years, he became disenchanted with the group because membership took too much time away from his family and the dues became too expensive for him to pay. 

Then, in the spring of 2013, he was injured in a motorcycle accident. He and his family moved in with his parents during his recovery and he said he never rode a motorcycle again. 

Despite his misgivings, Martinez testified that he didn't leave the club because he was worried he would be harmed, but the prosecutors disputed that with an expert witness, Darrin Kozlowski, who became a full-patch Mongol while working undercover for the Bureau of Alcohol, Tobacco and Firearms. 

Kozlowski, wearing a dark suit, glasses and a neatly trimmed goatee, testified that in his experience, all a Mongols member had to do to leave the club was make sure he had paid up all his dues. 

The prosecution and defense also argued at length about the undercover video and audio tapes officers used to try to get a confession out of Martinez as he was being transported to jail and in the jail.  

Prosecution witnesses testified that Martinez appeared to be boasting about shooting a police officer when he was talking to others in his cell, but public defender Sullivan wanted all the videos to be played for the jury, because they showed Martinez was consistent when he said he didn't know he was shooting at a police officer. Sullivan also argued that investigators were deliberately misrepresenting Martinez's statements to the jury.

The trial went nearly two weeks over the expected length. Testimony was slow because the attorneys on both sides often objected to their rival's questions, and Judge Charlaine Olmedo several times sent the jury out to admonish the attorneys for going beyond the boundaries of what she had established for the testimony. 

The case took years to get to trial, Martinez said during testimony, in part because his parents insisted he drop Sullivan, his public defender, and get another attorney who would put forward their belief that it was the police who had fired the fatal shot that day. 

His parents paid the attorney in advance, he said, and he stayed with him out of respect for what they had paid. But he and his parents had many arguments about what happened, he said, and he ultimately came back to Sullivan. 

Initially, Martinez said, he couldn’t accept that his bullet killed a police officer. He wanted to believe his parents' version of events, he said, his voice breaking, but “I've come to accept that I did shoot Shaun Diamond.” 

Photo: Officer Shaun Diamond is shown in a 2000 photo with his daughter, Margo. Credit: Family photo

June 21, 12:58 p.m. Correction: An earlier version of this article incorrectly said the first name of defense attorney Brady Sullivan was Blake. 

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