How an undercover former Army sniper foiled a murder plot concocted by KKK law enforcement members

GAINESVILLE, Fla. -- In 2015, three men, all current or former Florida correctional officers, were arrested after investigators revealed they were Ku Klux Klan members plotting to kill a Black former inmate.

Now, "Grand Knighthawk: Infiltrating the KKK," a new documentary and first-time collaboration between ABC News and The Associated Press takes viewers inside one of America's most sinister secret societies and the covert FBI operation to stop a modern-day lynching.

When the state of Florida announced the arrests of Thomas Driver, Charles Newcomb, and David Moran, it caught the eye of Associated Press journalist Jason Dearen.

"I just started looking into it and I kind of became obsessed with it."

"Grand Knighthawk: Infiltrating the KKK" is now streaming on Hulu.

Dearen wrote a series of articles about the case, piecing together information from court documents and interviews, but said, "there were just a lot of questions, a lot more questions than answers."

He knew that a confidential informant who infiltrated the klan had exposed the murder plot and led to the arrests, but he didn't know much else about this person.

"It was only after I wrote the second article in my series that I received an email and my heart stopped. The subject was, 'This is Joseph Moore.'"

In 2013, the FBI asked Joe Moore, a former Army sniper, to go undercover inside a local klan organization.

"We had been receiving a series of directives going back to 2006 concerning the threat from domestic terrorism extremism groups," said Chris Graham, the FBI Supervisory Special Agent in Jacksonville, Florida during Moore's recruitment. "The KKK has the history, the image, so to speak. They're capable and dangerous."

Moore said his mission was to "go inside the KKK to identify people that are involved and to forewarn the FBI of any illegal activities."

In order to join the Traditionalist American Knights of the KKK (TAKKKK), he embellished his military accolades and signed a blood oath. "They tell you that if you violate or disclose the secrets of the KKK, you'll pay with your blood."

Moore, 51, during an extensive interview with ABC News' George Stephanopoulos, revealed that he fears for his family's safety since his undercover operation.

According to Moore, even though his family was relocated and given new identities by the FBI, they have received threats from KKK members and supporters. He says he is coming forward now in an effort to protect them.

"If something were to happen to me, I need the world to know the truth," Moore said.

Produced by George Stephanopoulos Productions for ABC News Studios, the documentary features rarely-heard undercover audio and video from the investigation, firsthand accounts from FBI agents and the intended victim's mother, and intimate access and interviews with undercover source, Moore.

Moore spent his first year inside the TAKKKK gathering intelligence and learning the intricacies of the klan. Offering ABC News a look at confidential klan documents, Moore explained that the klan has an extensive language to weed out potential intruders.

"They use acronyms in order to ensure that impostors were not infiltrating the meeting or the klan. They would use terms like 'A.Y.A.K..' 'Are you a klansman?' And the proper response if you are a Klansman is, 'A.K.I.A..' 'A klansman I am.' If you don't respond with 'A.K.I.A.,' they know you're not a Klansman."

After rising through the ranks, thanks to his military background, Moore became the Grand Knighthawk for the Florida and Georgia realm of the TAKKKK, expanding his purview and connecting him with high-ranking klan leaders across the country.

The role made him the top security officer of the region's klan, among other, more nefarious, responsibilities.

"The Grand Knighthawk has been sort of a hitman for the KKK," said Moore. "I embraced the fact that the KKK might call upon me for violence."

Dearen's investigation into the organization found that multiple members had violent pasts. "The Klan tries to present a public face of being kind of a social club, but behind the scenes, oftentimes they're plotting violence," he said.

The news that Driver, Newcomb, and Moran were members of a white supremacist organization while working as correctional officers, may have surprised some, but according to Dearen, Florida law enforcement moonlighting as klansmen was nothing new.

Over the past decade alone, investigators discovered klan members working in local, county and state law enforcement agencies in Florida.

"These groups are trying to recruit law enforcement," said Greg Ehrie, the former FBI Section Chief of Domestic Terrorism Operations. "They're armed. They've had training. They have access to confidential information."

The extremist group's continued presence in Florida law enforcement agencies is in keeping with state history, Dearen said. Klan members ran towns and were sheriffs less than 100 years ago in Florida.

"You're not gonna surprise no Black person by telling them the klan is working in prisons, not southern Black people," said Antwan Williams, a former inmate of the Florida Department of Corrections.

Driver, Newcomb, and Moran all, at one time, worked at Florida's Reception and Medical Center, a state prison and hospital in Lake Butler.

It was at this correctional facility that Thomas Driver got into an altercation with the intended victim, Warren Williams.

Williams, who has a history of mental health issues, was serving time at the facility after hitting a police officer during a mental health episode. During their fight, Williams bit Driver.

According to Williams' mother, Latonya Crowley, Williams was beaten so badly by Driver that he was sent to the hospital.

Warren Williams grew up in North Florida, in a town called Palatka, on the St. John's River. Crowley said that as a child, Williams enjoyed spending time outdoors, especially fishing.

Williams spent a year in prison and came home to his mother's house, the fight with Driver still heavy on his mind.

"He said, 'Momma, ain't nobody will ever hear my story,'" Crowley said. "I was like, 'Okay, well, sit down and tell me your story.'"

The fight was still on Driver's mind, too. He had to undergo routine testing for communicable diseases, like HIV and Hep-C, after Williams' bite.

"Because of the worry over whether or not he picked up one of these diseases, he said it had caused his family immeasurable stress and that he just wanted this guy assassinated," Dearen said.

In December 2014, at a cross burning in rural North Florida, the three men approached Moore with a request. Driver told Moore about his fight with Williams and handed him a piece of paper with Williams' information on it.

"I asked, 'What do you want to do?' Moore said. "'Do you want him six feet under?' And they said, Yes.'"

Up until that moment, Moore's time undercover had been largely uneventful, but that night would change everything.

After their conversation, Moore said he immediately called his FBI handlers to warn them about the potential murder plot.

"Everything about that meeting was chilling," said Graham. "It's not illegal to engage in hateful speech. What is illegal is to go from hateful speech into the planning of a criminal act, a violent act."

"The KKK wanted to catch my son, cut him up in pieces on the creek, and leave him there," Crowley said.

"It was obvious that they did harbor racial animosity toward the victim," said Paul Brown, a former FBI Supervisory Special Agent. "There was absolute intent to see this carried out."

Realizing the severity of the threat, the FBI formulated a plan, getting Moore to continue discussing the would-be murder with the klan members, this time wearing a wire.

"He's obviously interacting with and around people that have expressed a clear intent to commit murder," Brown said. "If it came out that Joe was cooperating and working with the FBI, we feared his life could very well be in danger."

Over the next several months, Joe Moore would find himself pushed to the edge - balancing two lives and desperately racing to stop this murder.

"I've asked myself time and time again if knowing then what I know now, would I have done it again?" Moore said. "Ultimately I know I would say yes."