FBI has spoken to whistle-blowing officer in city and to private investigator, opening way for full-scale inquiry

The FBI is investigating whether police covered up the truth about what really happened when a black teenager was shot twice in the back while handcuffed by a white officer who claimed there was a struggle for his gun.

Daily Mail Online can reveal that FBI agents have begun looking into the 2011 death of Ariston Waiters.

Police Officer Luther Lewis, of Union City Police Department in Georgia, shot Ariston Waiters twice in the back as he was handcuffing the 19-year-old who face down on the ground on the night of December 14, 2011.

There were no witnesses to the close-range shooting and Lewis claimed the teen tried to grab his gun during a 'struggle'.

A grand jury refused to indict the officer for murder in May 2012, and he left the police department in 2014.

Questions: Ariston Waiters was shot twice in the back while being handcuffed by a Union City police officer.

But new evidence has since been unearthed contradicting the official account and casts doubt on the officer's version of events.

And senior officers at the Union City Police Department have been accused of covering up Lewis' actions.

The evidence - uncovered by private investigator TJ Ward, the man who recently found a new witness in the Natalee Holloway case - raises serious questions about how officials investigated Waiters' death, one of more than 100 fatal police shootings in Georgia in the past five years.

And it is feared the new details – which have angered Waiters' family and the Union City community - could spark racial tension - and rioting - similar to what happened in Baltimore and Ferguson.

Waiters was shot in the back twice and killed after running from the scene of teenagers fighting in a Union City neighborhood.

But the first officer on the scene has revealed that Lewis did not mention a struggle for his gun and told a very different story just minutes after it happened.

Scene of death:

Left force: Officer Luther Lewis, pictured as a member of the Union City PD SWAT team, was cleared by a grand jury after Ariston Waiters' death but is no longer in uniform

Two separate people told Daily Mail Online they have been questioned by the FBI within the last week. The Bureau had previously closed its inquiries into the death, but the new involvement opens the way for a new, full, investigation.

The inquiry is likely to center on two findings made by a private investigator who looked into the death on behalf of the dead teenager's family.

TJ Ward, who earlier this month uncovered a new witness in the mystery of the disappearance of Natalee Holloway, found inconsistencies in the account Lewis gave at the time.

And a serving police officer, Union City Police Lt. Chris McElroy, has come forward as a whistleblower to raise his concerns over the events surrounding Waiters' death.

Both men told Daily Mail Online the FBI had been in touch with them.

Lt McElroy said: 'The FBI spoke to me on Friday and I know they spoke with another officer. They told me they had a meeting at the US Attorney's office later that day.

'I just hope that it is looked at more thoroughly to make sure that there is nothing inappropriate that occurred.'

Private investigator TJ Ward said: 'The FBI has already interviewed three witnesses in detail, that happened Friday.

'The FBI also called me and they've got my reports.'

On December 14, 2011, Lewis was on early evening patrol with his partner Thomas Ledford when they responded to teenagers fighting and reports of gunshots at Hickory Lane Circle, a known trouble spot.

According to The Atlanta Journal-Constitution which quoted police reports, Lewis said he saw Waiters flee the area, and followed him to the woods.

Carrying both a Taser and a Glock 17 handgun, Lewis drew his gun and ordered Waiters to the ground. Waiters complied, Lewis said.

With one handcuff on, the officer called in a Code 4 – 'no assistance needed'. What happened over the next 60 seconds became the focus of months of investigation.

Lewis said that he put a knee between Waiters' shoulders, grabbed his hands and radioed that he had a suspect in custody.

Then he handcuffed Waiter's left hand, he said. But when Lewis tried to cuff his right hand, Waiters was able to break free and slide his right hand underneath him, Lewis said. When Lewis couldn't pull the hand out, he thought Waiters was going for a gun. Lewis said he pulled his Glock 17 handgun from his service holster.

His left hand still cuffed behind his back and still on his stomach, Waiters grabbed Lewis' gun with his right hand and started to twist the gun back toward Lewis, Lewis said.

Whistle blower: Union City Police Lt. Chris McElroy, who was the supervising officer, said Lewis told him that he shot the teen because he refused to pull his hands out from under him.

Tramatized?: Officer Luther Lewis had served in both Iraq and Afghanistan. Colleagues had highlighted erratic behavior which could have been linked to it

'That's when my soul went white,' Lewis said. 'That's when I knew I was losing my gun and that's when I knew I was fixing to die by my gun tonight. And I knew I wasn't going to let that happen, anything I could do to not have that happen.'

Lewis pushed back and fired off two quick shots into Waiters lower back.

But Lewis' version of events was at odds with the forensic evidence later compiled in the case.

The two bullets that killed Waiters entered his back at a near 90 degree angle and at close range, according to an expert.

Both bullets pierced Waiters' liver and one also hit his spine.

The expert eventually concluded that the shooting could not have occurred the way Lewis described.

Lewis was standing next to Waiters when McElroy arrived. The teen was face down with his hands handcuffed behind his back and gasping for breath every 15 to 30 seconds, 'like a goldfish out of water,' as McElroy later recalled.

Seeing the teen was badly wounded, McElroy put out an urgent call to get paramedics to the scene more quickly.

In those moments Lewis told McElroy he shot Waiters because he couldn't get the teen's hands out from under him and he thought he might have a gun.

At that point, McElroy told investigators, Lewis reached under Waiters to find out what he was concealing. He pulled out a pill bottle from Waiters' coat pocket.

When Lewis saw what it was, he threw the pill bottle down on the ground and exclaimed: 'That's it?' That's what you got shot for? That's it? That don't make sense.'

Campaign: Ariston Waiters' mother Freda has campaigned for a full probe into her son's death in December 2011.

Missed: Ariston Waiter with his daughter. His death in December 2011 was ruled not to be a criminal act by a grand jury, which cleared the officer who shot him, but is now being probed by the FBI

Lewis said nothing about a struggle for his gun, McElroy told investigators.

Officer Ledford, Lewis' partner, also told different versions of what happened that night.

In an initial handwritten statement, taken less than an hour after the shooting, Ledford did not mention any struggle for Lewis' gun, and he told a GBI agent on the scene that Lewis told him 'he had no choice; the subject kept fighting'.

Six hours later, back at police headquarters, Ledford told the GBI that as he arrived at the scene, Lewis told him that 'he didn't have a choice. He went for my gun.'

However his account differed from that of Lt McElroy, who was the supervising officer.

He said Lewis told him that he shot the teen because he refused to pull his hands out from under him - but the grand jury was not told of Lt McElroy's version of events.

McElroy and other key witnesses were never interviewed by the Union City Police Department or the GBI, which was called in to investigate the night of the shooting.

Somebody has got to do something to make this right. 'People need to have faith in the police department again and police officers. Not every police officer is bad.' Lt Chris McElroy

'I think Mr Waiters died senselessly and his family deserves some closure. I just don't think it's right. It's not sat right with me from the very first time I arrived on the scene,' McElroy told The Atlanta Journal-Constitution newspaper.

'I was surprised I didn't get called by the GBI [Georgia Bureau of Investigation].'

McElroy said he only learned about a struggle for Lewis' gun from Union City Police Chief Chuck Odom, who he said had met privately with Lewis at the police station hours later.

Concerned about Lewis' story McElroy said he asked Chief Odom the night of the shooting if he should write a statement about what he saw and did at the scene.

The chief said no, McElroy said. McElroy is speaking out now because he said it's the right thing to do and believes there has been a cover up.

'Somebody has got to do something to make this right,' McElroy said. 'People need to have faith in the police department again and police officers. Not every police officer is bad.'

According to The Atlanta Journal-Constitution a consultant hired by Fulton County District Attorney Paul Howard found Lewis gave changing official statements about the shooting to the GBI, so much so that he recommended indicting Lewis for false statements.

He also found that the forensic evidence did not support Lewis' version of events.

In the report, expert Michael Levine wrote that Lewis 'exhibited a disregard for human life that is unacceptable in professional law enforcement.'

A Fulton County grand jury heard Levine testify to his findings in May 2012, and Howard's office prepared an eight-count indictment against the officer, including felony murder, false imprisonment and violation of oath of office.

But the grand jurors refused to indict Lewis.

Freda Waiters, Waiters' mother, is furious that the jury was told all about her son's run-ins with police and his troubled mental history, but were told nothing about Lewis.

Months before he shot Waiters, Lewis reportedly threatened to shoot another black man because he refused to take his hands out of his pocket, Mr Ward told Daily Mail Online.

That decision is now at the center of the new probe after both the whistleblowing officer's new version of events and the conclusions of private investigator TJ Ward, who was commissioned by the family to investigate the case.

Campaign: Ariston Waiters' death has now been the subject of a lengthy campaign by his family for answers

Talks: Deacon Joe Beasley, Freda Waiters, and T.J. Ward at the State Attorney's Office following their meeting Freda - State Attys Office

He told Daily Mail Online: 'We are talking about a major cover up here right from the top of the police administration down.

'Ariston's mother is determined to seek justice for the death of her son.'

His concerns focus on both whether Lewis was

Using Layered Voice Analysis (LVA) technology, Ward said he first evaluated the statements made by Lewis himself to see if he was telling the truth.

Unlike the interpretation of body language signals, or polygraph analysis, LVA is a technology designed to detect 'brain activity traces' using the voice as a medium.

It is controversial, with questions over its validity, but Ward says that it is reliable.

'There's no question that Lewis is lying about what happened that day,' Ward says.

'It's impossible for the events that were documented by the officer to have actually taken place.'

He added: 'No reasonable person could believe that Lewis' actions were either out of self-defense or fear.'

It has also emerged that some of Lewis' police colleagues had concerns that the Afghanistan war veteran might have Post Traumatic Stress Disorder because of erratic behavior on patrol.

Several incidents reported by fellow cops should have acted as warning signs to police bosses.

Lewis, who joined Union City police in 2007, had spent eight years on active duty with the Army, which included a tour in Iraq, and later served in the Georgia National Guard.

Less than two years later after joining, Lewis was called up for military deployment and served a tour in Afghanistan.

He returned to policing in 2010 and was assigned to Union City's SWAT team and in 2011 the A.C.E. unit.

Waiters' death sparked protests in 2011 in South Fulton, but never drew the national attention that has followed the recent cases of deaths in police custody in of Ferguson, Missouri, North Charleston, South Caroline, and Baltimore, Maryland.

His mother has campaigned since the acquittal for a new investigation.

She told Daily Mail Online: 'Ariston was murdered in cold blood, like some stray dog on the street. The proof's all there, yet everyone is covering it up. Now I'm praying for justice for my son.

'This started back when the District Attorney through the Grand Jury did not indict the officer at the time which was three-and-half years ago.

'What happened from there was I got 4,500 pages of deposition for the whole case and started reading through. I was like "this is not right", what I was reading was unbelievable.

'I saw falsified examinations, people perjuring themselves, that's when I hired TJ Ward and he began to dig deeper and began pulling together all the inconsistencies.

'I want to see Luther Lewis indicted and charged for criminal negligence of my son and put away. And I want to see all the officers who perjured themselves and gave false information on my son, who were part of the cover up, I want to see them charged too.'

Freda, 56, said Waiters had been a challenging boy to raise and was diagnosed with bi-polar disorder at age 13.

He dropped out of high school, used drugs and had several encounters with police, including disorderly conduct.

Freda said that six months before his death, her son had become a father to a baby girl called Ajaleh and seemed energized by the birth, talking of returning to school so he could get qualifications to find a job.

Freda, who settled a wrongful death lawsuit on behalf of her granddaughter for $750,000, says she has a meeting planned with officials in Union City and will be asking for the chief of police to resign.

A spokesperson for the Georgia Bureau of Investigation said: 'We were requested by the District Attorney to reopen the investigation and we have done that, we have been conducting additional interviews with officers who claim to have information about the incident, we're doing this in conjunction with the District Attorney's Office.'