A military reservist is gunned down in his home in a gated community in Fallbrook, California near San Diego. After committing the cold-hearted crime, the shooter went out for casual breakfast.

Geoward Eustaquio was a real estate agent and a kids' rugby coach, living with his wife Laura and their two children and his older son from a previous relationship in an upscale neighborhood of Fallbrook, Calif., north of San Diego. Living in the guest house was Laura's mom, Cynthia Cdebaca.

"After her stroke Geoward wanted to make sure that Cynthia received the care that she needed, and what better place could be for her than to be among family?" said Geonisa Harris, Geoward's sister.

Three generations all living together, but they weren't "The Waltons." There were conflicts, most often between Geoward and his mother-in-law.

Cynthia was a smoker, something Geoward detested.

"My brother did not want Cynthia to smoke in the presence of his children," said Geonisa. "He believes that 'If you're going to stay in my home, then you have to abide by my rules.'"

"My Aunt Cindy would be on the back patio smoking 'cause she wasn't allowed to smoke in the house, and he would be out there watering and he would go, 'Where I see smoke, I see fire, gotta put out the fire,' and he would hose my aunt down with the hose," said Sabra Cabrera, Cynthia Cdebaca's niece. "He did it to my cousin too, he did it to his wife. He would hose her just because she maybe didn't say something he didn't like."

And another recurring issue, Cynthia believed Geoward, a military reservist, was way too strict with his kids.

"My brother would tell me that she didn't approve of the way he disciplined the kids. On the other hand my brother didn't approve the way she would discipline his kids," said Georanna Biroonak, Geoward's sister.

Typical family problems? Perhaps. But it probably wasn't easy for Cynthia's daughter, Geoward's wife Laura, who often found herself in the middle.

But Feb. 11, 2014 was supposed to be different: It was Geoward's daughter's spelling bee and Cynthia's 63rd birthday.

But the spelling bee and birthday celebrations would never be, when the piercing sounds of gunfire changed everything.

Concerned neighbors call 911. As deputies quickly descend on the quiet enclave, a trail of blood leads them to the Geoward Eustaquio, dead inside his house, shot multiple times.

George Eustaquio learns there's an emergency at his brother's house and rushes there, not knowing what horror awaits him. George calls family on the East Coast to give them the dreadful news.

"My mother lost just about every breath she had, and despite losing her breath, the words she uttered will haunt me for the rest of my life: She said 'That woman, Laura's mother, killed my son,'" said Geonisa.

Military reservist Geoward Eustaquio was shot more than 10 times by his own mother-in-law, Cynthia Cdebaca. Hours later detectives find Cynthia celebrating her birthday at her favorite coffee shop, and they take her down to the station.

"She did come into the police station in a very jolly, jovial kind of way, happily greeting the police officers, kind of like 'Hi, what's going on? What brings me here?'" said George.

Cynthia is about to learn exactly what brings her here.

"Something happened today at your house and unfortunately, Laura's husband -- you know what Laura's husband's name is?" a detective asks Cynthia during a recorded interrogation. "Well, unfortunately Laura's husband has passed away."

Cynthia appears confused. She cries and appears upset -- but the tears quickly turn to contempt. Asked what she things of Geoward, she gives detectives a big "thumbs down" gesture. Cynthia tells detectives Geoward has been abusive to her, her daughter Laura and her grandkids, for years, saying Geoward has sprayed her with water, tripped her and choked Laura.

So clearly Cynthia was not Geoward's biggest fan, but it's what she says next that really blows detectives away: She admits she "stopped him." She says "I was guilty. Somebody had to stop him."

Cynthia: Is he dead?

Detective: You tell me.

Cynthia: He's gotta be dead.

Detective: Do you think he's dead?

Cynthia: I hope so.

What reason does she give for committing this homicidal act? Detectives learn the final straw for Cynthia was a comment Geoward made that morning before his daughter's spelling bee.

"He said 'You can't go like that because it looks like you're "ghetto" in this,'" Cynthia says. She says she went and shot him, but "it wasn't enough."

Geoward never saw the first shots coming. He was shot in the back. Cynthia was just getting started.

"After she fired all five shots out of that revolver, she chose to go all the way to her car and reload five more rounds into her gun," said San Diego County Deputy District Attorney Keith Watanabe. "She walked back into the back yard and found the victim bleeding and crawling, trying to get away, and at that time she pumped five more shots into his body. She still wasn't done. She still chose to go to her car, load five more rounds. At that time the victim had crawled his way into the house and into the kitchen. She pulled out that revolver and fired five more shots until the victim was finally dead."

Cynthia emptied her .38-caliber revolver three times, stopping to reload twice. She tells detectives she remembers firing 15 rounds. Of those 15 bullets fired, 12 hit her son-in-law, killing him.

Detective: Did he say anything to you?

Cynthia: 'Oh grandma, I love you.'

Detective: Did you check to see if he was dead?

Cynthia: I didn't care.

"She went and enjoyed her birthday," said Watanabe. "She went to Denny's and enjoyed a breakfast there. She went to Pechanga and gambled for two hours, and then went and enjoyed some coffee at a coffee shop until she was finally contacted by detectives from the sheriff's department."

Cynthia: Is he alive?

Detective: No.

Cynthia: Oh good, good, good, good, good, good. Oh thank you!

Detectives aren't the only ones hearing Cynthia's heartless confession. Geoward's family also hears it through the sheriff's station's walls.

"As I was sitting there I heard along with my other family members, she loudly said 'Yes! I shot him!'" said George, Geoward's brother. "We all just stared, like, We just can't believe she did it."

Detective: You don't feel bad about it?

Cynthia: No.

Detective: Would you do it again?

Cynthia: Yes.

With that exceptionally enthusiastic admission of guilt, detectives allow family members to come in and say their goodbyes. Laura -- Geoward's wife, Cynthia's daughter -- is inconsolable. Geoward's young daughter -- Cynthia's granddaughter -- can barely make it in the room. She refuses to embrace her grandmother.

Cynthia Cdebaca is arrested and taken to jail. She was charged with first-degree murder.

"She had been planning this," said Keith Watanabe. "She actually had been to the shooting range two weeks earlier and had been practicing shooting with this very same gun."

Doctors evaluate Cynthia, finding her competent to stand trial. Finally, almost three years after Geoward was gunned down, the trial begins.

"You're going to hear throughout this case that she would refer to herself as 'Ghetto Grandma,' and I don't want to use that term in any disparaging way," Prosecutor Watanabe said in court. "She would call her that herself, even to her own grandkids."

"The victim's wife testified for the defense in order to support claims that the victim was abusive," said Keith Watanabe.

Many days and witnesses later, the case goes to the jury, and when everyone's back in court to hear the verdict, Cynthia is seen strangely waving to the judge.

But it doesn't help: Cynthia Cdebaca, 66, is found guilty of first-degree murder.

"She showed no remorse whatsoever," said Georanna Biroonak, Geoward's sister. "None."

At Cynthia's sentencing Geoward's sister Geonisa holds up 15 photos for the 15 shots fired.

Laura addresses the court: "I love my mom, she's not well, and I loved Geoward, too."

Cynthia Cdebaca is sentenced to 50 years to life in prison.

So the one question remains: Was there abuse?

"We looked into the various claims of abuse and we simply just determined that whether or not they were true, the defendant had no right to make herself the judge, the jury and the executioner. This was simply an act of vigilante homicide," said Keith Watanabe.

Now this family is suffering the loss of two of their own, one at the hands of the other.

"I still cry a lot. Not only did we lose Geoward, but we lost my aunt, too," said Sabra.

"The word 'monster' is even too good for someone like her," said Geonisa. "She's a devil. How could you do this to someone who permitted you to live in his home, and you did this without thinking about the consequences for your daughter, your grandchildren. That's the definition of a devil to me."