An Arizona mother is demanding justice for her dead son.
"I want the truth," said Roberta Johnson.
It's a case filled with twists and turns and a startling outcome.
The killer goes free when prosecutors say it was self-defense, and now you can see and hear the killer describe it all in his own words.
ABC15 Investigators obtained video of a police interrogation that provides an exclusive look at the killer's version of events.
Watch the raw video using the player above (WARNING: graphic images and explicit language).
This is a local case that, like the Trayvon Martin shooting in Florida , puts the issue of self-defense front and center and leaves a mother grieving.
Roberta Johnson's son Scott was only 25 when he was stabbed to death in Globe in 2010.
"You have to live without your son. You'll never see him again and he'll never get married and never have children," she said.
She wants the investigation of her son's killing reopened and the killer held to account.
"I think there is a self-defense-no-matter-what attitude in this area," Johnson told ABC15.
Through a public information request, ABC15 Investigators obtained the case file from the Gila County Attorney's office.
We reviewed police records and witness statements and we examined the evidence.
What we found raises questions about how this case was handled and how Arizona's self-defense laws are applied.
After a night out drinking, Scott Johnson was walking home when he decided to stop at a neighbor's house and visit two sisters he knew from high school.
But when he knocked on the door, the sisters sent Robert Verdugo outside to tell Johnson to leave.
There are only two eyewitnesses to what happened next and one of them, Scott Johnson is not alive to tell his side of the story.
Prosecutors say they believe Verdugo felt threatened by Johnson—a much larger man.
According to police reports, Verdugo's story has changed over time.
The night of the incident Verdugo told police Scott Johnson knocked on the door.
But in later interviews with investigators, Verdugo claimed Johnson tried to force his way into the house.
Gila County Attorney Daisy Flores says there is no evidence Scott Johnson tried to break into the house.
Verdugo told police he went back into the house after telling Johnson to leave.
When Johnson didn't leave Verdugo said he went back outside with his knife tucked in his shorts, records show.
In the police video, Robert Verdugo claims Scott Johnson swung first landing a blow to the side of his head, knocking him to the ground.
But police and prosecutors say Verdugo did not sustain any injuries.
Verdugo also told police his fight with Scott Johnson took place on the driveway of the home.
But Johnson's family disputes that.
Verdugo's account suggests the entire altercation took place near the carport.
But a veteran investigator hired by the Johnson family says the small droplets of blood in that area don't indicate the fatal wound was inflicted there.
Instead, the family's investigator, retired detective Bill De La Torre, suggests the stab wound that punctured Scott Johnson's heart and severed his aorta was inflicted more than 70 feet away on the street.
That's where crime scene photographs show a large pool of blood was discovered.
On the video you can hear a police officer ask Verdugo, "Where's the knife now?"
The investigator also asks Verdugo, "Did you feel threatened?"
What do you think -- was self defense justified? Vote in the poll attached above.
Another piece of evidence obtained by ABC15 Investigators was the 911 call from Verdugo's girlfriend the night of the fight.
"They're fighting, can you get someone out here please," Jessica Luna tells the operator.
But by the time police arrive Scott Johnson is lying on the street in a pool of blood.
He was flown to Maricopa Medical Center but doctors cannot save him.
Gila County Attorney Daisy Flores says her office and the Globe Police department did a thorough investigation and they determined that Robert Verdugo killed Scott Johnson in self-defense.
Scott Johnson's family say there was a rush to judgment the night of the stabbing and they say the police investigation was poorly handled.
They say the evidence does not add up to justify self-defense.
Scott Johnson's mother wants Robert Verdugo arrested.
In response to pressure from the Johnson family, Gila County Attorney Daisy Flores asked for an outside review of her decision.
The Pinal County Attorney's office agreed with Flores decision to decline to charge Robert Verdugo.
Flores told ABC15, "I believe he acted in self defense."
When asked about criticism of the police investigation, Flores admits, "It wasn't perfect."
Flores says police should have tested Verdugo for drugs the night of the incident.
ABC15 Investigators reviewed police reports that indicate the night he stabbed Scott Johnson to death Verdugo told police he took Ambien, methadone, Xanax, and Paxil.
also acknowledges Verdugo changed his story several times.
But Flores insists it is reasonable to believe Robert Verdugo felt his life was in danger.
Six years ago Arizona lawmakers changed the law.
Now prosecutors have the burden to prove that a defendant killed without justification—it all comes down to what is reasonable.
Flores said, "You don't have a duty to retreat in Arizona. He reasonably believed that deadly physical force was necessary to protect himself".
But Scott Johnson's friends and family do not agree.
They want the case reopened.
Roberta Johnson said, "I don't think taking a six-inch hunting knife to an argument…is normal or reasonable."