fbpx Pomona police Archives - Hey SoCal. Change is our intention.
The Votes Are In!
2023 Readers' Choice is back, bigger and better than ever!
View Winners →
Nominate your favorite business!
2024 Readers' Choice is back, bigger and better than ever!
Nominate →
Subscribeto our newsletter to stay informed
  • Enter your phone number to be notified if you win
  • This field is for validation purposes and should be left unchanged.

Home / Pomona police

San Gabriel man gets 10 years for Pomona police officer’s death


A man who pleaded no contest to voluntary manslaughter for the fatal shooting of a Pomona police SWAT officer who was helping to serve a search warrant at a San Gabriel house where the defendant and his family lived was sentenced Tuesday to 10 years in prison.

Defense attorney Brady Sullivan, who had asked for the 10-year sentence, told reporters outside court that David Martinez has already served the bulk of the term and is expected to be released from custody on or before March 26.

Martinez was acquitted in two separate trials — first of first-degree murder and then of second-degree murder stemming from Officer Shaun Diamond’s October 2014 shooting death.

Jurors in the most recent trial deadlocked last October on the lesser count of voluntary manslaughter and a charge of assault with a firearm on a police officer, with Martinez subsequently pleading no contest Nov. 30 to both of those counts and admitting gun allegations.

“The truth of the matter is it was a tragic accident,” Martinez told Superior Court Judge Charlaine F. Olmedo shortly before she imposed the sentence.

The defendant said he was “deeply sorry” for his involvement in the 45-year-old officer’s death and understands the pain and anger felt by those close to Diamond.

Martinez, who testified in his own defense during both of his trials, told jurors in his first trial that he fired a “warning shot” from his shotgun because he feared members of the Mongols motorcycle club — an organization to which he belonged — were trying to break into the home he shared with his parents, his girlfriend, their two young children and his adult sister.

“I kept saying I was sorry. I didn’t know it was the police,” Martinez testified in 2019. “I thought it was the Mongols. I would never fire at police or law enforcement ever. I have family that’s (in) law enforcement.”

Diamond — a 16-year law enforcement veteran who had also worked for the Los Angeles and Montebello police departments — was placed on life support Oct. 28, 2014, and died a day after the bullet severed his spine and shattered his lower jaw. His organs were harvested in what Deputy District Attorney Jack Garden called “one more act of helping others.”

The prosecutor called on Olmedo to impose the maximum 33-year term, saying that Martinez “told lie after lie under oath” and was “able to fool numerous jurors.”

“He aimed and fired that 12-gauge shotgun at Officer Shaun Diamond,” Garden said, noting that the officer was walking away and didn’t even have a gun in his hands. “The defendant took no time to consider his own father was in the way of his shotgun. He fired that shotgun and he didn’t care.”

Sullivan countered that he believed the 10-year sentence was a “just outcome” in a “very complicated case.”

“I firmly believe that David would never deliberately shoot a police officer,” the defense lawyer told the judge, saying that his client has paid a “huge price” and that he believes his client’s actions will weigh on Martinez’s conscience for the rest of his life.

The slain Pomona police officer’s daughter, Margo Diamond Nelson, told the judge, “I don’t wish David any harm, but I do hope that he is haunted by what he did. … I don’t need to forgive David and I never will. He will always be the person who murdered my father. That will never change.”

She said she had to watch her father die and held his lifeless hand as the man she said was “so much more than just a police officer” was taken off life support, and never thought this would be the outcome of the case against Martinez.

The officer’s sister, Melody, called him “my hero” and said she will “forever have a hole in my heart,” while his brother, Christopher, said that he had been robbed of the opportunity to share so many things with him.

The officer’s ex-wife, Tristine Devine, maintained, “It was not an accident. It was not self-defense.”

Pomona Police Department Capt. Ryan Rodriguez told the judge that he was on a fishing trip when he was notified about Diamond’s shooting and wondered if things would have been different if he had been working that day, but said “it’s nobody’s fault, but Mr. Martinez.”

Los Angeles County Sheriff’s Homicide Detective Ray Lugo pleaded with the judge, “Don’t let him go home soon. … Please, you need to send him to prison.” He said Martinez “pretended to be a good guy, but he’s a fake.”

The judge called it a “tragic case,” saying that the officer “did not deserve to die” and that two juries did not believe that Martinez acted in justifiable self-defense even though jurors acquitted him of first-degree murder and subsequently of second-degree murder.

Olmedo — who said she had to balance the aggravating factors with the mitigating factors and impose the mid-term sentence — noted that Martinez was initially facing life in prison if he had been convicted of murder and that jurors had given him his life back. She urged him not to betray the love and support of his family, who have steadfastly been in the downtown Los Angeles courtroom throughout both of his trials.

Martinez has remained jailed since he surrendered to police shortly after the shooting, telling officers, “I’m sorry. I didn’t know you were the police. I thought you were the Mongols.”

Police went to the house early that morning to serve a search warrant as part of an ongoing investigation by a task force into the Mongols, Deputy District Attorney Hilary Williams told jurors during the retrial.

Diamond had turned his back to walk off the steps with a heavy piece of equipment that had been used to open the screen door and was shot by Martinez in the back of the neck, the prosecutor told jurors during the trial. None of the other officers present returned fire, the prosecutor said.

“You don’t get to just shoot somebody on your doorstep,” Williams told jurors, arguing that there was no way the shooting occurred in self- defense as Martinez and his attorney contend.

The deputy district attorney told the panel that it was “irrational on every level” to shoot a law enforcement officer in front of some of the defendant’s own family members, but said the defendant was “high on methamphetamine” at the time of the shooting.

Martinez’s attorney called what happened a “tragic accident” and said Martinez was lawfully defending his family after seeing the barrel of a gun.

“And it was reasonable. … The law says it’s reasonable to defend your family, your home and yourself,” Sullivan told the panel.

Martinez’s lawyer said it was not reasonable to believe Martinez would deliberately fire a shot at police and put his entire family at risk inside the home.

“He didn’t know it’s the police. He thinks it’s an intruder,” Sullivan said.

The defendant told jurors he was startled to hear screaming after firing the shot, turned around, dropped the shotgun and laid down.

The defense attorney called the Pomona police SWAT team’s operation that day “completely unnecessary” and contended that the officers’ warnings that they were there to serve a search warrant were drowned out by noise being made by the SWAT team as they tried to get into the house and a locked gate. The prosecutor countered that the warnings were given before and during the efforts to breach the home and gate.

Outside court after the sentencing, Rodriguez with the Pomona Police Department said, “Seeing that Mr. Martinez took our brother’s life, of course, we would have liked to see a punishment that was more just.” He said their job now is to make sure Diamond’s legacy lives on throughout the years.

Skip to content