Law Enforcement Life in General

Pomona Police Officer Killed in 15-Hour Stand-Off With Suspect, Who is Reportedly a Mentally Ill Vet

Celeste Fremon
Written by Celeste Fremon

Pomona PD Officer Greggory Casillas was sworn in only six months ago, and was nearly finished with field training. Yet, on Friday, the 30-year-old officer who is married and the father of two young children was shot to death at the beginning of what would become a 15-hour stand off with a suspect who barricaded himself inside a Pomona apartment, then began firing on officers.

“It’s a sad day for the Pomona Police Department, and it’s a sad day for our community, and its a sad day for law enforcement in general,” said Pomona PD Chief, Michael Olivieri in a grim press conference where he announced that one of his officers had died.

Officer Casillas had been working for the department in civilian positions since 2014, beginning as a record specialist then, the following year, becoming a jailer. Finally he applied for his dream job, which was to become a sworn police officer. Casillas received his Pomona Police Department badge in September 2017.

Pomona PD Chief, Michael Olivieri and LA County Sheriff Jim McDonnell at Sat. press conference, courtesy of the LASD.

According to Chief Oliveri, the newly minted cop felt that taking his earlier positions working for the force would prepare him to be a better police officer when he reached his ultimate goal.

An ordinary-appearing incident turns deadly

The incident began at around 9 p.m. Saturday night when two officers responded to a call that someone was driving recklessly. They located the driver of the vehicle, a truck, but instead pulling over, the man raced away, and a chase began. As the chase continued, the driver crashed his truck into another vehicle near an apartment complex in the 1400 block of Palomares Street in Pomona.

After crashing, the suspect took off on foot into the courtyard of the complex, as the two officers ran in pursuit, then he disappeared into an apartment inside the building.

The two officers approached the apartment, intending to contact the suspect and make an arrest. Instead, the suspect opened fire on through the closed apartment door, hitting one of the officers.

The second officer rushed in to pull his wounded comrade to safety. But as he did so, the suspect fired again, hitting him in the face.

Deadly 15-hour standoff in Pomona, courtesy of LASD SEB

At first, Pomona PD officers could not extract the two wounded officers because of additional gunfire. Eventually, they succeeded and both were rushed to Pomona Valley Hospital Medical Center.

One officer was taken quickly to surgery, but he is expected to recover.

Casillas, however, was pronounced dead at the hospital.

In the meantime, the Special Enforcement Team from the Los Angeles County Sheriff’s Department arrived on the scene to support the Pomona PD, as did officers from various other agencies*, as the deadly incident turned into a lengthy stand-off.

As the long hours pass

LASD Mobile Command Post, courtesy of LASD SEB

According to a statement from the LA sheriffs, the LASD’s Crisis Negotiations Team members made verbal attempts to persuade the suspect to surrender, but the man would not comply.

SEB deputies reportedly used various diversionary tactics, including flash bangs and tear gas, yet the suspect remained barricaded.

Finally, the SEB team entered the location where the suspect was hiding, “and deployed LASD K-9.”

This ultimately led to the suspect, 39-year-old Isaias De Jesus Valencia of Pomona, being taken into custody, dressed only in his underpants. He was booked for suspicion of murder of a police officer and attempted murder of other peace officers. of a police officer and the attempted murder of other peace officers, and is being held on $1 million in bail.

Reports of mental illness

ABC7’s reporters spoke to a resident at the scene who said he knows the gunman and described him as a father of three who is battling severe depression.

“He’s a family man. He’s faced with mental illness…” Amos Young told the reporters.

In later interviews Young described Valencia as having been in “extreme need of mental healthcare” since his return from the military.

Other neighbors told LA Times reporters that they spotted a woman they said was the suspect’s mother who was crying and vomiting outside the apartment building, and soon after got into a police SUV.

Honoring the fallen hero

Earlier in the day, fellow police stood and solemnly saluted as a line of patrol cars from Pomona, San Gabriel Valley, and elsewhere, followed the body of Pomona PD Officer Greggory Casillas from the hospital to the office of the Los Angeles County Coroner.

“He left his family at home to protect yours,” Chief Oliveri told those gathered at a press conference after the suspect had been arrested. “His ultimate sacrifice will never be forgotten.”

Pomona PD Chief, Michael Olivieri

Governor Jerry Brown ordered flags at the Capitol to fly at half-staff in honor of the slain officer.

“Anne and I are saddened by the tragic death of Officer Casillas,” Brown said in a statement on Saturday. “His brave sacrifice will never be forgotten.”

Chief of the Los Angeles Police Department also commented on the Pomona officer’s death.

“Another hero gone too soon,” he said. “These tragedies are occurring too often, and the pains of sacrifice will never be forgotten.” Beck said that all the members of the department he leads “will be wearing black mourning bands” to honor Greggory Casillas.

Post Script

In writing this extremely painful story we were reminded that, on average, law enforcement officers killed the line of duty leave behind two children, just like Officer Casillas.

As of today, 17 U.S. law enforcement officers have been killed by gunfire in the line of duty.

Top image of Officer Casillas being sworn in is courtesy of the Pomona Police Department

*Updated Monday, 3-12-2018, 11:32 a.m. to make clear that multiple local law enforcement agencies came to help the Pomona P.D.


  • Prayers go out to the families of both Officers. Kudos to LASD Special Enforcement Bureau for their expertise and professionalism, which is second to none.

  • Let me guess… AB109 success story? A formerly deported a
    illegal alien? When will the politicians take responsibility for failing to protect the citizens of California?

    • This story is a tragedy all around, why do you try to compound it with a cheap shot like that? The suspect is a US citizen, a military veteran, so that didn’t help Officer Casillas at all, did it? Citizenship didn’t help the Vegas, Sandy Hook, or Florida shootings either, did it? AB109, Prop 47, and Prop 57 all have their origins in the heady days of the 1980’s, where “lock em’ up and throw away the key” was the rage for ALL politicians. The bill came due, and here we are today with no resources and even less voter will to pay for the incarceration level required to keep the really bad off the streets.

      • LATBG:
        Great call. A cheap shot is correct. Many are quick to politicize and blame, without doing their due diligence and homework.

  • What many of us forget is the years of pain for the children as they grow. Sadly, thanks to Jerry Brown, there is No Death Penalty!

  • Surely refreshing for once to see an unbiased article on WLA. Every LEO funeral you attend makes you say, “This is the last one I will attend,” but it never is.

    • Personal opinions of WLA should be a stand alone statement in another forum, not riding on tails of a tragic incident.

  • I’m sorry, “due diligence and homework?” This isn’t the standard of WLA with this type of stuff though the one comment was off. Celeste is a “Valley Girl” and this is not hers and I doubt yours but be free to argue that with me. Gee, if I remember an AB109’er thanks to our “catch and release” policies of the legislative left and dumb downed voters allowed a felon to do 5 10 day bites and eventually gun down his cousin and a Whittier cop, smart thinking you soft on crime people. They all know with the reductions of felonies to misdemeanors it’s a cite and out the door or a few days in and back on the street and some, end up killing. same with 72 hr holds, useless.

    Mistakes and misconceptions are written here, this was a 999, lots of agencies rolled. Geez, you would think it was only LASD out there, it wasn’t but of course they rocked like they do when called upon. Hell Riverside S.O. rolled along with just about every local agency, team effort securing this location and as outside agency units were rolling up another large exchange of gunfire took place between Pomona officers and the suspect. I can not say enough about the heroics and bravery of these Pomona guys, incredible. But Pomona has never lacked for guys who could step to the plate and have dealt with a population filled with lots of scum, read a little on the town, not a secret.

    What do you think this guy was doing as they lobbed in their devices folks, just sitting around? Interview anyone Celeste to find out? Send any of your ace staff out there to find out to actually dig a bit? I mean it was only an O.I.S. where a cop was gunned down and did you try? This is LOCAL! Just wondering or did you just get what you wrote from what you saw and read?

    See that’s my gripe with you. This is important stuff to me, to all cops I know, this hit way close to home, way close.

    By the way, this many officers gunned down didn’t happen until May last year but two things. You wouldn’t see a story about that here and wouldn’t have heard about this if it happened in No.Cal., not a chance.

  • Another commenter used the term “hall monitor” to describe those who attempt to shame others into silence. That’s as good a metaphor as anything I can think of. Try arguing ideas, rather than pointing and sputtering “you can’t say that!” Looking at you Leo

  • He was kicked out of the military after a short stint. I would hardly call that a VET. Also, he has an extensive criminal history and recently discharged parole. The liberal “mentally ill VET” argument won’t fly. I’m sure when the true facts are disclosed, the media, as usual, won’t report it.

    • Don’t disdain the media, Dulce. The media reported the crimes of your hero, convicted felon Paul Tanaka. No, you and your alter ego “Boomer” are not forgotten. Four years ago with you being one of his cheerleaders when he was a candidate for Sheriff, it would be best to get a new pen name.

  • Here you go. So apparently the piece of shit who killed the Pomona officer was arrested three years ago for being a felon in possession of a firearm and discharging said firearm in a school zone. He was sent to state prison and released after year on PRCS. He had since discharged that probation.
    Someone can correct me if I’m wrong but what I’m hearing.

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