Oxygen Insider Exclusive!

Create a free profile to get unlimited access to exclusive videos, breaking news, sweepstakes, and more!

Sign Up for Free to View
Crime News Snapped: Killer Couples

Teen Couple Goes On L.A. Murder Spree, “Wipes Out” Family in Bloody Rampage

When honors student Monica Diaz, 16, met boyfriend Michael Naranjo, 17, in a high school ROTC program, their connection quickly turned sinister.

By Grace Jidoun

There’s nothing more disturbing than murder, but when teenagers commit it against their own family, it’s unimaginably horrifying. What drove a “straight-A” high-school couple, Monica Diaz, 16, and Michael Naranjo, 17, to brutally murder Monica’s dad and her three younger siblings, and nearly stab her mom to death?

How to Watch

Watch Snapped: Killer Couples on Oxygen Sundays at 6/5c and on Peacock. Catch up on the Oxygen App.

“Effectively, an entire family was wiped out. That was startling,” said 30-year LAPD veteran Detective Bill Marsh on Snapped: Killer Couples, airing Sundays at 6/5c on Oxygen.

The latest episode of Snapped: Killer Couples takes a closer look at the infamous Los Angeles killings that were so brutal the Pico Rivera community thought it may have been the work of a serial killer.

“I felt like we had the perfect family,” said eldest sister Esperanza Flores on Snapped: Killer Couples.

Her parents, Richard and Sylvia Flores, had a total of four biological children, ages 10 to 18, and had adopted their nieces Monica Diaz and Laura Reta as small children when their mom passed away.

The family of eight loved sports, with many of the children involved in athletics, and their small suburban house was the “central hub for everything. Never a dull moment. Always someone laughing,” Esperanza recalled.

What happened to the Flores family?

It was the summer of 2000, and Esperanza was home from college.

“Nothing seemed out of the ordinary” on the night of July 20 until a loud thud on her bedroom wall woke her up early the next morning. Thinking it was an earthquake, she ran outside into the hallway.

Richard And Sylvia Flores featured on Snapped: Killer Couples Episode 1720

“I saw my dad holding his neck, and there was blood everywhere,” she recalled on Snapped: Killer Couples. “He was stabbed so bad you could see parts of his insides coming out. And I knelt beside him. There was so much blood my knees were literally soaked in his blood.”

Monica, 16, was in the bathroom when she called 911 and told police her family was being attacked. When authorities arrived and did a protective sweep of the house, they found one gruesome crime scene after another.

Sylvia Jr., 14, had suffered “horrific” injuries while being stabbed to death in her bedroom, recalled Detective Marsh. Brothers Richard, Jr., 17, and Matthew, 10, were also killed in the bedroom they shared.

More true crime:

Army Vet Fatally Shot Man His Girlfriend Had Told Him Molested Her: "I Pulled the Trigger 7 or 8 Times"

Cold Justice Aids in Arrest of S.C. Couple Suspected of 2015 Halloween Quadruple Murder

Gypsy Rose Blanchard Shows Off New Look, Reveals the "Tiny Things" She Loves Post-Prison

Marsh has handled 300 homicide cases in his long career, but this one brought him to tears.

“It’s my belief that Matthew was more than likely awakened during the course of this event. He obviously fought. His body was lying, resting against his brother … I remember catching myself because I didn’t want my tears to fall in and co-mingle DNA on this young man.”

Monica Diaz featured on Snapped: Killer Couples Episode 1720

The fifth victim, dad Richard, Sr., had numerous defensive wounds on his body, which indicated he fought back when attacked in his bedroom. His wife, Sylvia, was lying next to him and miraculously survived despite her windpipe having been cut.

“When you see multiple injuries to a body, it can support ... the belief that it was done with great rage. There was passion involved in this,” remarked Marsh.

How was Monica Diaz caught?

Marsh immediately noticed a red flag at the crime scene. Sylvia “had a piece of duct tape affixed to her mouth. The presence of duct tape made me go, OK, this is not a random event. This is a planned event,” he recalled.

More evidence made the detective do a double-take. Two knives were found in plain sight on top of the vanity where Monica "hid" during the attack. He then noticed the kitchen door was unlocked and found a backpack stashed nearby with a towel that would later connect her boyfriend, Michael Naranjo, to the crime scene.

Michael Naranjo featured on Snapped: Killer Couples Episode 1720

“I’m looking at the survivors, and something in the back of my head is going, maybe one of these young ladies is involved,” said Marsh.

At first, investigators had sister Laura in their crosshairs.

“I think multiple people said, ‘Look at Laura, she might be the person,’ and it was only because I was always in trouble,” she lamented to Snapped: Killer Couples. “I was always doing my own thing… but I could never hurt a human being.”

Soon, attention turned to Monica when she told detectives her boyfriend, Michael, gave her a knife.

Who is Michael Naranjo?

The teens had met in the Junior Reserve Officer Training Corps (“ROTC”) program in high school and fell in love.

Michael dreamed of joining the Marines one day, and Monica was an honors student enrolled in AP classes, but their connection quickly turned sinister.

During a second search of the Flores home, investigators uncovered a box of disturbing letters between the young couple. In one letter, shown on Snapped: Killer Couples, Monica describes killing as her “life’s work.”

She wrote: “I want to see the blood on their faces. I want to be a mass murderer … The best job is to kill people professionally [sic]. I mean Hitler only lived for a few years and he killed lots, though he did it the cowardly way. Imagine how many victims I’d have if I lived 800 years?”

According to Marsh, some family acquaintances said Monica was treated differently because she wasn’t as “athletically gifted. She was looked down on.” Her boyfriend, Michael “had problems with the mother. He would call her out, [say] ‘she’s a bitch.’”

But nothing could quite explain their obsession with murder. 

A search of Michael’s home also turned up a tsunami of evidence, including a bookcase dedicated to getting “schooled in the art of being a trained killer,” said Marsh, with guides on murder, torture, hand-to-hand combat, military manuals, and lock-picking.

But even more damning, police found a notebook with a murder check-off list, an extensive array of knives, and a towel that matched the one found stashed in a backpack outside the Flores kitchen door.

Just three days into the investigation, the forensics results came in. A bloody flashlight found in the Flores hallway had Michael’s fingerprints on the batteries. What’s more, every single piece of duct tape found at the crime scene was covered with Michael and Monica’s fingerprints.

After their arrests, when they were in the squad car together, neither showed any remorse, just concern for themselves.

“So, this is our last time together?” Monica asked in an audio tape replayed on Snapped: Killer Couples.

“You don’t know that. I love you, baby,” replied Michael.

Meanwhile, Sylvia was regaining consciousness at the hospital after surviving the attack, and she recalled to Snapped: Killer Couples in an emotional interview that she saw a male attacking Richard in the bedroom and running off.

“Monica was all of a sudden there. And I said, 'Go get a towel,' and she went to the bathroom and got a towel, and I said, 'Put pressure.' And then I felt her hands reaching for my throat, and she was applying a lot of pressure. I grabbed her arm,” said the grieving mom and wife. “She was trying to finish me off. But I didn’t let her. No, not today.”

Why did Monica Diaz kill her family?

Los Angeles investigators seem just as stumped as family and friends. When asked why he did it, Michael said of the family, “I liked them; I had nothing against them. I just wanted to kill someone.”

Michael tried to claim all responsibility and even took the stand in Monica’s trial to plead her innocence, but the jury didn’t buy it, according to Detective Marsh.

In October 2003, Michael confessed right before his jury trial began. He was sentenced to five consecutive life terms and will be eligible for a parole suitability hearing in 2027.

More than a year later, Monica claimed innocence at her jury trial but was sentenced to four consecutive life terms, but that was overturned in 2005. She was later resentenced to four consecutive terms of 25 years to life. Her parole eligibility was recently denied in 2022.

“He loved her. What do you do for love?” pondered her sister Laura on Snapped: Killer Couples. “Some people do anything they can. He made her feel that good, and she manipulated him into doing what she wanted."

Latest Videos