Fire crews rush to a house fire call in Pueblo, Colorado, but they found much more than just flames and smoke. They uncovered a deadly plan that would rip a loving family apart.

For Susan Hernandez, 77, her family was everything.

"She raised seven children," said daughter Katrina Livecchi. "We were her life. We were her world."

"She was a beautiful person and a wonderful mother, a wonderful grandmother," said daughter Brenda Lovato.

It was six months since the love of Susan Hernandez's life, Carlos, her husband of 59 years, had died. To keep her company in her Pueblo, Colorado home was her dog, and daughter Vanessa, who lived right across the street. Katrina, who lives about 45 minutes away, talked to her mom daily.

Katrina says her mom hadn't been sleeping well. She'd been stressed about the new roof she'd hired her grandson Anthony Sena, Vanessa's son, to put on.

Shortly after 7 a.m. Wednesday, July 28, 2015, Katrina called her mother, who did not pick up. She called her again at 7:15 a.m., but no answer. Katrina tries her again later, but still nothing.

"I had a horrible gut feeling going through my stomach," said Katrina. "I closed up my house and drove down to Pueblo."

When Katrina arrived at her mother's house, she was greeted by clouds of smoke. She sees the smoke is coming from the basement. Katrina immediately makes a gut-wrenching call to 911 to report the fire and the appearance of a break-in. She goes outside, but the intense need to find her mom pulls her back in. She finds her mother's body on fire in the basement of the house.

Pueblo Police Detective Raymond Purvis, who is assigned to the case, comes from a storied law enforcement family: He's a relative of famed FBI agent Melvin Purvis, considered to be the man who got gangster John Dillinger.

As Detective Purvis approaches the house, he immediately notices signs of forced entry. It appeared someone had kicked open the door. Inside, things seemed to be untouched. He made his way to the basement. Susan Hernandez had been set on fire. Investigators would soon learn she had sustained obvious trauma to the back of her head. Susan Hernandez had been bludgeoned.

"She had a large hole to the back of her head," said Det. Purvis. "She had been struck multiple times and we knew that because of the cast off and the blood splatter at the scene. We definitely knew it was a homicide, there was no question about that."

Katrina's sister Brenda was at work when she got the news. She arrived, and other distraught family members also showed up to the horrific scene. There along with Brenda and Katrina is their sister Vanessa, who lives across the street, her sons Devin and Anthony, and their cousin Sebastian.

While police canvass the neighborhood, family members are escorted to the station for routine questioning.

Cops get other leads and learn when Susan was last seen alive.

"Supposedly she was last seen the day before, earlier in the morning walking her dog," said Det. Purvis. "There was also a neighbor that stated she had maybe saw a suspicious male who walked back and forth up from the river. We were also told that the night before there were some lights on in Mrs. Hernandez's house. It was just unusual for her to have the lights on, she was going to bed usually pretty early, and the lights stayed on throughout the night."

So the canvassing of the neighborhood yielded some valuable information. Hopefully talking to Susan's family will help investigators get them closer to catching the murderer.

"We had them all transported down to the police station, and began to interview them as witnesses," said Det. Purvis.

At the Pueblo Police Department are Susan's daughters, Katrina, who found her mom, Brenda Lovato and Vanessa, who lives across the street from her mom. Also at the station are Vanessa's sons -- Susan's grandsons -- Devin and Anthony, and their cousin Sebastian.

"We were just trying to find out why Mrs. Hernandez was killed," said Purvis. "She had no enemies. Everyone loved her, so it was kind of confusing to us why somebody would want to do that."

Then a theory starts to take shape.

"We were told that Mrs. Hernandez had a cash box that had potentially a large amount of cash in there," said Purvis. "The first time we were searching that house we did not locate that cash box, so at this point in time it was appeared that it could have been a possible burglary."

The distraught family members are all brought to different interview rooms.

"I was assigned to interview Anthony Sena, which is Susan's grandson," said Det. Purvis.

Anthony Sena was the one who was supposed to redo Susan Hernandez's roof. She'd been stressed out about it, causing her to have some sleepless nights.

While waiting for Purvis, Anthony notices the cameras and switches seats. He then receives a call. Then he makes a call. Minutes later, Det. Purvis comes in to start the interview.

Purvis establishes that Anthony saw and talked to his grandmother on Monday. Anthony then tells Purvis he went to her house again on Tuesday, this time with his brother Devin and his 10-year-old daughter. But on Tuesday she didn't answer the door or any of his calls that day.

But back to the roofing job, a job he was going to do with his brothers Bruce and Devin and cousin Sebastian. Anthony says his grandmother had written him two checks, one for the materials and one for the labor. He tells Purvis the total was $7,600. He tells Purvis he's already purchased the materials, but then can't remember from where.

"The story was starting to not make some sense," said Purvis.

Anthony starts to get flustered. Anthony had done time some prison time for stealing, vandalism and the armed robbery of an armored car.

"Anthony was in trouble all the time since he was little," said Brenda. "I believe he was on an ankle bracelet since he was like 11, and he was proud of it."

The interview then takes a more serious turn. Purvis asks Anthony directly if he had anything to do with the crime. Anthony says no. He tells Purvis he thinks he's being scrutinized because of his past.

Eventually Anthony gives Det. Purvis consent to search his phone.

As Anthony sits alone in the interrogation room, he talks to himself, saying "I shouldn't have." Then he vomits into a trash can.

When Purvis returns, he asks Anthony if he was at his grandmother's that morning. Anthony says he went by his mother's house around 6:45 or 6:50 a.m., but says she wasn't there. His mother, Vanessa, lives across the street from the crime scene. He says he has nothing else that would help the investigation.

Eventually, Anthony and his other family members are free to go. Then a couple of nights later a woman approaches some officers on the street.

Officers wearing body-cameras go to the woman's house. It's Vanessa, Anthony's mother. She tells police she's worried about someone coming after her if she says something.

"Oh God, I can't think it 'cause I'll end up dead like my mom," she says on the recording from the body-cam. "I think it was all about money, he's psycho, he's f------ psycho. I know, I know he killed my mom."

But who is she talking about?

"I don't want to die. If we say anything he's going to come after us," she says.

The officers ask her if she's been drinking.

"Oh yeah," she says. "I don't have no proof that he did it, I don't know anything about that. I just have it in my heart that he did."

"We did not have a murder weapon at that time," said Det. Raymond Purvis. "There wasn't nothing at that house a whole lot that we could go on."

So it was going to take some old-fashioned legwork, and some video surveillance to help solve this heinous crime.

"Mrs. Hernandez had been seen at a store in the area around noon, maybe 12:30, so at that time that she was alive around 12:30, and that she was potentially not alive around 2:30 or 3, because she wasn't answering her phone," said Purvis.

So investigators believe she was killed on Tuesday, July 28 between noon and 3 p.m., then set on fire the next day.

A week later, the family is back at the police station for some routine fingerprinting and photographs. Detective Purvis is once again assigned to Anthony Sena.

"So as we're walking down the hallway he stops me and he says 'You don't have anything on me, if you had anything on me you'd arrested me by now,'" said Purvis. "And he looked at me and said 'You know God stopped that fire, and I said, 'No,' I said, 'The firemen stopped that fire.' But I thought about it for a minute and I said 'You know what? I think God did stop that fire, Anthony, I think you're right.'

"She was probably burning for no longer maybe than a few hours," said Purvis. "Whoever had done this at that time shut that basement door when they set her on fire. And there was really not enough oxygen to get down to that basement to really ignite the flames. So it was a big break that whoever did this did not let a bunch of the oxygen fuel the fire, because we probably would have had the entire house on fire."

And that misstep led investigators to an absolute bombshell.

"The body had not been totally burned or consumed, so there was one hand that had some fingernails or fingers left to it, and when the pathologist had taken the samples from underneath the fingernails we did send them off to CBI, which later came back as Y-STR DNA," said Purvis.

Y-STR DNA is DNA found only in males. And when the results come back from the lab, this Y-STR DNA identified five potential suspects.

"Anthony Sena, Devin Sena, Bruce Sena, Sebastian Sena, and we had Joseph Sena, which is the father," said Purvis.

"So we knew that it was one of the Sena members," said Purvis. "We just didn't know which one had actually committed the crime, or maybe all at this point in time, we didn't know. So we began on working to rule out each one and try to find the true person who did this."

Although cops are looking at all five of these Sena men, clues keep bringing them back to just one: Anthony.

Anthony's mom Vanessa had talked to officers before, and she had more to say.

"One night we got a phone call from her stating that she had found the murder weapon," said Det. Purvis. "She identified this hammer that was in her kitchen as the potential murder weapon. She believed her son Anthony could have possibly put it there."

Cops take the hammer in for testing but can't link it directly to the murder.

Then a break: A man finds Susan Hernandez's identification and some other cards of hers lying on the side of the road. Phone records eventually place Anthony near the road where the cards were found. Phone records also place Anthony near the house the morning of the fire.

The leads keep coming, this time from Anthony's little girl.

"His daughter had stated that the day that Anthony met Devin over to talk with grandma, when her dad came back to get her and they were driving, she saw some blood on his ear," said Purvis.

As detectives are closing in on Anthony, they're simultaneously ruling out the other Sena men through phone records, witness statements and alibis.

"It was evident to us that Anthony was pretty much the lone person in the case," said Purvis.

It isn't looking good for Anthony.

So what was Anthony's motive? Cops learn it may have all stemmed from money and a roofing job that never was.

"Anthony took the money from my mother, never made good on the roof," said Katrina. "He kept giving her the runaround."

Katrina says her mom told Anthony many times she wanted her money back.

"And she told me that if he doesn't bring the money back by Tuesday, she's calling the cops," said Katrina.

Tuesday she was dead.

"The walls were closing in on Anthony at that time," said Det. Raymond Purvis. "He didn't have the money. So he had an option: 'I can try to get the money, or I can potentially go ahead and kill grandma and make it look like someone else did it and that will be my way out.'"

Cops bring Anthony back in for questioning, and this time he tries to strike a deal.

"He suggested that he would give us the money back and we would call it a day," said Purvis. "We told him we could take the money back but we still have to look at the murder."

Investigators continued following leads to build a case. Eventually the missing cash box is found hidden in Susan's closet. And the other Sena men, one by one, are all subsequently cleared of any wrongdoing. To detectives, Anthony Sena is their man.

"I think he did it with intent," said Purvis. "I think he did it with deliberation and I think he committed cold-blooded first-degree murder."

After a four-month-long investigation, Anthony Sena is arrested at his house for the murder of his own grandmother.

The trial lasts two weeks. After four hours of jury deliberation, Anthony Sena is found guilty and sentenced to life in prison without parole.

"Anthony Sena almost got away with this murder," said Purvis. "If the hand had been burned, this case probably and could likely have gone unsolved."

"Every day of my life, every morning I wake up, I relive that day, every day. She was my life, she was everything," said Katrina. "I will never forgive him for what he did to my mother."