Moment former detective confronts convicted child killer he put on death row two decades ago as case takes shocking twist

A former detective has apologized to a man he helped convict and put on death row for killing his two-year-old daughter.

Robert Roberson III, 57, was sentenced to death after he was found guilty of shaking his daughter Nikki Curtis to death at his home in Palestine, East Texas, in 2003.

He is currently in a legal fight to overturn his conviction - claiming a debunked medical hypothesis and his undiagnosed autism put him behind bars.

Amid Roberson's battle for his life, former cop Rev. Brian Wharton met up with him in a Texas prison in a harrowing confrontation filmed by The New York Times.

'Let me just say, I am so sorry that you're here and so sorry that you're still here,' Wharton told Roberson. 'It's our failure.'

Former detective Rev Brian Wharton has apologized to a man he helped convict and put on death row for killing his two-year-old daughter

Robert Roberson III, 57, was sentenced to death after he was found guilty of shaking his daughter Nikki Curtis to death at his home in Palestine , East Texas , in 2003

Wharton, who was the chief detective in Palestine at the time, has come to regret his role in Roberson's conviction and is working to help overturn it and save his life.

'He's never been far from my mind. Why?  Because I helped put him here, and he didn't deserve it,' Roberson told the NYT.

Wharton recalled thinking that Roberson's demeanor seemed strange when he brought Nikki to the hospital, claiming she was unconscious after falling from the bed.

That's when hospital staff started discussing shaken baby syndrome and Roberson was arrested, tried and convicted.

'I've never been able to forget Robert Roberson. This case has been a burden on my heart and spirit

'Let me just say that you have never been far from me, and I'm convinced that we did the wrong thing

Roberson, seen here with his daughter Nikki, was prosecuted on what is now a widely discredited understanding of Shaken Baby Syndrome

Roberson replied: 'I think if it would have been properly investigated more, we wouldn't be sitting here now, probably

It was bad enough losing her, right? I would do anything now to bring her back

Wharton admits that no other causes of death were considered for Nikki, and that police 'followed the easiest path.' 

He later learned that Roberson has autism which could have explained his lack of emotion over Nikki's death - but never came out during trial.

Nikki was also a 'very sick child,' according to Wharton, who now thinks some of those medical issues could have explained her death.

Most importantly for Roberson's defense,  shaken baby syndrome has been discredited by many in the medical community. 

Prosecutors - and the jury - at the time determined she had died not from a fall but from being shaken to death by her father. 

But in the years since, doctors have stepped away from assigning shaken baby syndrome (SBS) as a cause of death.

Roberson was a parolee at the time of his daughter's death with previous convictions for burglary and theft and parole violations

The scientist who proposed it himself even admitted that it was being used to 'put innocent people in prison', warning in 2012 'we have gone badly off the rails.'

Roberson was given custody of Nikki by her maternal grandparents after her mother, who has remained unnamed was denied custody in the hospital after her birth.

In the week prior her death, Nikki had been sick and appeared at a local emergency room where she was prescribed Phenergan and sent home.

After her condition didn't improve, doctors again prescribed her more Phenergan and codeine, an opioid now restricted from children under the age of 18.

At the time of his conviction in 2003, the consensus amongst the medical community was that Nikki must have been violently shaken and possibly struck

Phenergan now comes with a warning against being prescribed to children of Nikki's age.

The following night she had gone to sleep beside her father, who woke up to find her unconscious.

Roberson was a parolee at the time of his daughter's death with previous convictions for burglary and theft and parole violations.

Multiple women testified that they'd seen Roberson shake and 'spank' Nikki when she cried.

Among them were his girlfriend at the time, her daughter, and her niece. All of them claimed they had seen Roberson lash out at his daughter.

Prosecutors initially said Roberson sexually assaulted Nikki, based on statements from a hospital nurse, but dropped that element of the capital murder charge late in the trial 

Teddie Cox, his then girlfriend, testified that Roberson had a bad temper and would frequently shake and spank Nikki when she wouldn't stop crying.

Cox's niece Courtney Berryhill also told the trial that when she spent the night at the home she witnessed Roberson shake Nikki by the arms to stop her crying.

While Cox's daughter Rachel testified that she had witnessed him spank and shake Nikki, and also recalled a time he threatened to kill his daughter.

Prosecutors initially said Roberson sexually assaulted Nikki, based on statements from a nurse, but dropped that element late in the trial when evidence could not conclusively support it.