Judge orders mistrial after jury deadlocks on whether Mongols member killed Pomona SWAT officer in 2014

David Martinez is pictured in Los Angeles Superior Court during his his arraignment hearing in 2014.
(Irfan Khan / Los Angeles Times)

After nearly two months of testimony and deliberation, a Los Angeles Superior court judge on Friday declared a mistrial in the murder trial of a Mongols Motorcycle Club member after a jury deadlocked over whether he acted in self-defense when he fatally shot Pomona police SWAT officer Shaun Diamond in 2014.

The jury reached a unanimous verdict of not guilty in the first-degree murder charge against David Martinez, but deadlocked 3 to 9, with the majority in favor of acquittal, on the charge of second-degree murder.

The jury never got past their deadlock to discuss the other two charges of voluntary manslaughter and assault on a police officer, the jury foreperson, identified only as Juror No. 3, told Judge Charlaine Olmedo in open court Friday afternoon.

The foreperson had tears in her eyes as she left the courtroom. Later, Juror No. 3 declined to give her name, but she said she was frustrated that the jury couldn’t acquit Martinez because three jury members were determined to find Martinez guilty because he was a member of the Mongols.


The juror said she had close family members in law enforcement and struggled with acquitting a man accused of killing a police officer, “but I took an oath to be fair and impartial,” she said. “For me it didn’t matter if he was a Mongol. It was just what makes the most sense and what fits with the evidence.”

Martinez, who has been in custody since the shooting Oct. 28, 2014, will remain in jail as attorneys decide their next steps. A hearing has been set for July 11 to consider new motions in the case.

Prosecutors Jack Garden and Michael Blake declined to comment on the verdict. “The D.A. will make a decision about how we proceed,” Garden said.

Martinez’s attorney, Public Defender Brady Sullivan, said he would be requesting a motion to dismiss under Penal Code 1385, which allows the judge to dismiss a case “in the furtherance of justice.”


Family and friends of Martinez and Diamond listened silently and mostly without expression during the proceedings. None were willing to comment.

Diamond, a popular and well-respected Pomona police officer, had been in law enforcement for 16 years when he was killed. He started with the Los Angeles and Montebello police departments before joining Pomona’s in 2006 as a patrol officer. He became a member of the Pomona SWAT team in 2008, a job he loved, his daughter Margo said during a break in the trial.

He was shot as he and 13 other Pomona SWAT officers were moving in on Martinez’s house in the 100 block of North San Marino Avenue in San Gabriel to serve a search warrant as part of a multiagency operation targeting the Mongols Motorcycle Club.

Diamond was pronounced dead the following day from a single shotgun slug that entered at the back of his neck, severed his spinal cord and shattered his jaw.

Investigators testified that the shot also grazed the arm of Martinez’s father, Arturo,

The prosecution and the defense agreed that when police entered the house less than a minute after the shooting, Martinez was lying on the floor, gun tossed aside, shouting, “I’m sorry, I’m sorry. I didn’t know you were the police. I thought you were Mongols.”

But that was about the only point of agreement during six weeks of often contentious testimony. The jury faced a stark choice when the attorneys finished their closing statements in the early afternoon of June 21:

Did Martinez deliberately kill Diamond to enhance his reputation in the Mongols Motorcycle Club and then quickly concoct an alibi, as the prosecution alleged, or did he shoot once in self-defense, unaware that the people breaking into his house that morning were Pomona SWAT team members?


Martinez testified that he kept a loaded shotgun under his bed because he was worried about attacks by rival gang members and even some members of the Mongols, with whom he’d recently argued. He had stopped paying his dues, he testified, and no longer rode his motorcycle after he was injured in a bad accident, but was afraid of reprisals if he tried to quit the club.

He said he never heard anything but a loud banging and the family’s four dogs barking when he ran to the living room with his fully loaded shotgun. He shouted futilely to his father, Arturo, to “Wait, wait,” as his father opened the front door, he said. He saw “shadows” outside, he said, and what appeared to be the barrel of a gun pointing inside, so he fired his gun.

Garden, one of the prosecutors, ridiculed the defense contention that Martinez didn’t hear the SWAT team announcement (“Pomona Police Department search warrant— open the door!”) or recognize them as police.

Martinez was standing about five feet from the door when he fired his weapon, Garden said. The porch light was on, and the officers wore green jumpsuits with the word “POLICE” emblazoned in bright yellow letters.

“Officer Diamond was 6-2. He was a big guy,” Garden said, “How do you not see Officer Diamond on the porch with the light on?”

But Sullivan, the public defender, said officers testified that they had entered the house about 15 seconds after the shooting and it was “ridiculous” to think that Martinez concocted an alibi in that short time, in the midst of the chaos and his father’s injury.

And while the house may be small enough to fit in the courtroom, he said, investigators ran tests at the house and couldn’t prove the officers’ announcements could be heard in the bedroom over the banging and dogs barking.

“If David is this crazed Mongol who came up to the door with his shotgun loaded with 14 bullets, why did he only shoot one?” Sullivan said. “If someone is that crazy, that he’s going to open fire on the police, with his family all around him, why wouldn’t he keep shooting?”


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