WARNING: THE FOLLOWING CONTAINS SPOILERS FROM AN UPCOMING DOCUMENTARY.

It was 2007 when John Mimbela, a Texas-based contractor, decided to help a man he believed was innocent of a double murder.

He had just married the former sister-in-law of the imprisoned man, Daniel Villegas, and adopted his three nieces.

"When we would take our daughters to visit their grandparents, which are Daniel’s parents, I would hear them talk about a son who was in prison but was innocent," Mimbela told Fox News. "Yet he had a life sentence. I didn’t pay a whole bunch of attention at first. I just figured, of course, no one wants to accept the fact that their son was in prison for murder.”

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Daniel Villegas claimed police "harassed" him into giving a false confession. — ID

Daniel Villegas claimed police "harassed" him into giving a false confession. — ID

“But one day… they were just very torn up,” Mimbela continued. “They were just crying. When I asked what’s wrong, they said, ‘Our son is never getting out of prison.’ I felt so bad. I thought, let me see what I can do. I started looking into the case and I became convinced that there was a very big possibility that Daniel was innocent.”

The shocking case of Villegas, a man who at age 16, under what he claimed was intense police pressure, took responsibility for a double homicide in the city of El Paso, is the subject of a new Investigation Discovery (ID) documentary titled “A Fatal Confession: Keith Morrison Investigates.”

The investigative journalist explores how Villegas became imprisoned at age 18, sparking a fight for justice. It features interviews with Villegas and his family, as well as investigators associated with the case.

Late one night in 1993, four young men were walking home from a party when a car pulled up beside them and someone from the passenger side began shooting. Robert England, 19, was shot once in the head and died in the street. Armando Lazo, 17, was shot in the abdomen and thigh. He made it about 100 yards to a nearby home, where his body was found. The other two, Jesse Hernandez and Juan Medina, survived but could not identify the shooter.

A young Daniel Villegas. — ID

A young Daniel Villegas. — ID

According to The National Registry of Exonerations, Detective Alfonso Marquez of the El Paso Police Department brought in David Rangel, 17, for questioning. Rangel said that others had wrongly implicated him and that, if he didn’t come clean, he would spend the rest of his life in prison. Rangel told Marquez that his cousin, Villegas, had said he had shot Lazo and England with a sawed-off shotgun — but added that he was sure the teen was joking, as he often boasted about things that he hadn’t actually done.

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Villegas was later arrested and taken to Juvenile Investigative Services, where he was handcuffed to a chair, questioned and threatened. A terrified Villegas agreed to give a statement. He recanted his confession a few hours after signing his statement. Villegas told a juvenile probation officer that he was innocent and only confessed because the police “were harassing him.” Villegas was charged with capital murder.

Mimbela, who has no experience in criminal law, initially questioned Villegas’ innocence, but after reviewing court documents he realized something was very wrong.

John Mimbela participated in a new Investigation Discovery documentary about the case of Daniel Villegas.

John Mimbela participated in a new Investigation Discovery documentary about the case of Daniel Villegas. (ID)

“When I started looking into the paperwork, I saw that there was no physical evidence whatsoever that connected Daniel to this crime and that the only thing out there was a confession that did not match anything to what the police report said happened or any of the witnesses," said Mimbela. "I figured there had to be a mistake. Maybe they overlooked something and would want to correct it — do the right thing and give Daniel a fair trial.”

Villegas’ first trial, in 1994, had ended in a mistrial. He was retried and convicted the following year. Villegas was sentenced to life in prison.

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Mimbela said he hired a private investigator to further help him dig into what happened that tragic night. Mimbela said the facts showed that Villegas did not commit the murders. Determined to help, he called the media to present his findings, set up billboards to raise awareness and supported rallies. He also helped raise funds for Villegas’ legal defense. According to the Texas Tribune, Mimbela also amassed the help of expert witnesses, exonerated individuals, lawyers, investigators and the innocence group Proclaim Justice to further prove Villegas was innocent.

(ID)

“Daniel tells me they had him convinced that the only way out of that interrogation was if they told them what they wanted to hear,” said Mimbela. “They would let him go. If not, he was going to get the ultimate punishment, the death penalty. He didn’t have any other option but to confess. What these people think in these interrogation rooms is, ‘I’m going to tell them what they want to hear now, but I know that later on, they’re going to investigate everything and they’re going to see that this is not true.’ These people don’t know about the consequences. They think that it’s going to get straightened out.”

The Texas Tribune shared Mimbela and supporters pointed out that another shooting had occurred right before the slayings and the same type of weapon was used. They alleged the same killer might have been involved in both crimes. Joe Spencer, Villegas' lead attorney, alleged police used physical, mental and emotional abuse to get a confession out of the teen despite lack of forensic and physical evidence, as well as eyewitness testimony.

The district attorney told the outlet the investigation focused on Villegas because he did tell his cousin he committed the murders despite claiming he was merely joking.

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John Mimbela said he later believed Daniel Villegas was innocent. — ID

John Mimbela said he later believed Daniel Villegas was innocent. — ID

“My wife had grown up with Daniel,” said Mimbela. “My wife always said he was a jolly guy, always a kidder… When I went to visit Daniel, he just didn’t strike me as a killer. He was a joker… I just could not see this evil, angry person. He did not strike me as somebody who could commit a crime like this.”

An appeals court in 2013 overturned the conviction and a trial was ordered. In 2018, after serving 18 years in prison, Villegas was found not guilty in his third and final capital murder trial. Villegas, 41, collapsed in tears after hearing the verdict in an El Paso courtroom.

“My God, that moment is very hard to describe,” said Mimbela. “… We were sitting down. Had we been standing like Daniel, we would have also had the same reaction — knees trembling, falling to our feet. I never prayed so hard in my life.”

The El Paso Times reported a jury of seven women and five men deliberated for about nine hours before reaching their decision. After the verdict, Villegas and his family went to pray at St. Mark Catholic Church. Prosecutor James Montoya told the outlet that despite the verdict, the El Paso County District Attorney’s Office maintains that Villegas is responsible for the two deaths. He added there are no other suspects and “no one else to investigate.” Prosecutors cannot appeal the acquittal.

A young Daniel Villegas in court. — ID

A young Daniel Villegas in court. — ID

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Mimbela said he hopes the documentary will show people that the judicial system is far from perfect.

“I do believe our system is one of the best in the world, but there’s a lot of room for improvement,” he explained. “I think we need to thoroughly investigate these cases. Anytime there is a confession, they need to be corroborated.”

“There are some people who get caught up, like in Daniel’s case,” continued Mimbela. “Mistakes are made. We need to realize that. And we need to give these people the benefit of the doubt… What is wrong with investigating new evidence, testing new DNA to make sure you have the right person? I don’t understand why anyone wouldn’t fight for something like that. I want to believe they want the real person behind bars and not an innocent person locked up for any amount of time.”

Jan. 14, 2014: Daniel Villegas waves as he leaves county jail in El Paso, Texas. Villegas, convicted in 1995 for the murder of two teens, was released on bond after a court of appeals ruled his defense was inefficient during the 1995 trial.

Daniel Villegas waves as he leaves county jail in El Paso, Texas. Villegas, convicted in 1995 for the murder of two teens, was released on bond after a court of appeals ruled his defense was inefficient during the 1995 trial. (AP)

"A Fatal Confession: Keith Morrison Investigates" premieres July 7 at 9 p.m. on ID. The Associated Press contributed to this report.