EXCLUSIVE: A Texas death row inmate is scheduled to be executed next week for his conviction of killing his 2-year-old daughter in 2002, but his lawyer argues that not only is her client innocent, nobody is responsible for the little girl’s death.

Robert Roberson is scheduled to be executed by lethal injection on Oct. 17. Prosecutors said his daughter, Nikki Curtis, was killed after sustaining injuries caused by being violently shaken, known as shaken baby syndrome. Roberson would be the first person in the U.S. to be executed based on shaken baby syndrome.

More than 80 Texas state lawmakers, as well as the detective who helped the prosecution, medical experts, parental rights groups, human rights groups, bestselling novelist John Grisham and other advocates have called for the state to grant Roberson clemency over the belief that he is innocent. A group of state lawmakers even visited him in prison to encourage him.

In an exclusive interview with Fox News Digital, his longtime lawyer, Gretchen Sween, says shaken baby syndrome has been debunked and that Nikki’s actual cause of death has been revealed to be from other health issues such as pneumonia, which is a lung infection.

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Roberson, who has maintained his innocence, took his daughter to the hospital in 2002 after he woke up and found her unconscious with blue lips. Doctors at the time were skeptical of Roberson’s claim that his daughter had fallen off the bed while they were sleeping, with some testifying at trial that her symptoms were consistent with the signs of shaken baby syndrome.

“I believe he is innocent for two distinct reasons,” Sween told Fox News Digital. “The theory that there was a crime that was used to convict him, which was then known as the shaken baby syndrome hypothesis, has been thoroughly discredited. There is no one now who would say the version of that hypothesis that was put before his jury as if it were scientific fact is legitimate.”

“Also, I know from the experts that had dug into his daughter’s medical records and examined the evidence that this exceedingly ill child died from undiagnosed pneumonia that was [ravaging] her lungs, combined with very dangerous prescription medications she was given in the last few days of her life,” she continued. “And it’s not to suggest that doctors did this intentionally. It’s just they didn’t know about the pneumonia.”

The doctors, she says, observed Nikki’s symptoms and believed they suggested a cold or flu, and they gave her an antihistamine and codeine, medications that suppress breathing.

“Pneumonia is a disease of the lungs,” Sween said. “You have this child struggling to breathe given these medications, and she collapses and ceases breathing in the night. We now know what happened to this child, and we know what the state said happened 20-something years ago is just not true.”

Many medical professionals, including those from Stanford University Medical Center, University of Pennsylvania and Children’s Minnesota Hospital, now say that doctors diagnose shaken baby syndrome too soon before taking into account a child’s medical history.

Sween said it is “maddening” that there is what she believes is “overwhelming” and “compelling” evidence that the courts have yet to examine.

The Texas Court of Criminal Appeals previously halted his execution in 2016. However, last year the court allowed the case to resume, and a new date was set to carry out Roberson’s death.

On Monday, Roberson’s lawyers asked a Texas court to stay his execution and reconsider his innocence based on new scientific evidence. His lawyers also urged the court to reconsider its previous denial of habeas relief based on new evidence that further shows how a groundbreaking state law designed to prevent wrongful convictions was not applied as intended in his case.

Sween says she will make every appeal she knows to make to help spare her client’s life, up to and including the U.S. Supreme Court.

Texas law allows the governor to grant a one-time, 30-day reprieve from execution. But full clemency requires a recommendation from the majority of the Board of Pardons and Paroles, which is appointed by the governor.

Since GOP Gov. Greg Abbott was sworn into office in 2015, he has granted clemency in only one death row case, when he commuted Thomas Whitaker’s death sentence to life in prison an hour before his scheduled execution in 2018. Whitaker had been convicted of arranging a plot that left his mother and brother fatally shot and his father wounded.

But Sween says Roberson’s case is different from previous death penalty cases because it is an “actual innocence case,” where not only was Roberson wrongly accused, but there was no crime at all.

“If that doesn’t merit a use of executive power, I don’t know what does,” Sween said.

Abbott’s office and the Board of Pardons and Paroles did not respond to Fox News Digitals’ requests for comment.

Prosecutors maintain that the evidence against Roberson remains sound and that the science of shaken baby syndrome has not changed as much as his defense argues.

“That’s just not defensible,” Sween said of prosecutors’ claims the science has not changed. She also noted that the American Academy for Pediatrics, which she says is responsible for the shaken baby syndrome becoming widely known, states in its current consensus statement that abuse must not be diagnosed until every other possible cause of the same conditions is eliminated.

She also said there is no proof that shaking caused Nikki’s symptoms and cited multiple studies showing that there are several other possible explanations for the child’s death. She also pointed to studies showing that there has never been a case where shaking can cause internal bleeding outside the brain or a brain injury.

Sween also pointed out that Nikki, at2-years-old, was not a baby and the anatomy of a 2-year-old is different from that of a baby.

Shaken baby syndrome was theorized years ago as a possible explanation for mysterious deaths of infants who suffered internal head conditions, subdural bleeding, brain swelling and sometimes retinal hemorrhages. But Sween says the theory was never tested and was still treated as established fact.

“Now we know all these medical conditions can cause the same symptoms,” she said. “So how can you say abuse can be diagnosed when something like pneumonia can cause the same internal condition? So, I think respectfully, the state is simply wrong in this.”

Sween also cited a similar case in a different part of Texas that was tried a couple of years before Roberson’s. In that case in Dallas, which featured the same child abuse expert that was used in Roberson’s case in Palestine, Texas, prosecutors representing the state conceded the science has changed and agreed that that man deserves a new trial.

Roberson’s attorneys have also argued that his demeanor was wrongfully used against him, as he is autistic. He did not seem like a distraught parent, which Sween says can be attributed to his autism.

“This started when he brought his child to the hospital,” Sween said. “She was comatose. He didn’t know how to explain her condition. His demeanor, from the outset, was judged as just odd, off, weird. There are all these judgments made that then became part of the trial testimony. Multiple witnesses told the jury that this was a reason to suspect him, his off demeanor. Now, of course, none of these doctors or nurses or law enforcement knew that Robert had autism.”

Part of autism, Sween says, is that a person may often shut down when they have a crisis of emotion and do not show the emotions they feel on the inside. She said this was the case with Roberson, who was not diagnosed with autism until 2018.

“And that was his condition, and it stayed, but there are even references to this in his records way before this happened with Nikki,” she said. “But he’d never been properly diagnosed. He’d been, you know, a special needs kid, poor kid, living on the edge of town, got some help through Medicaid, was put in special ed classes, but he was never given a thorough diagnosis, a workup to figure out what was going on.”

Roberson said the outpouring of support from various people and groups who believe he is innocent has made a difference to him, according to Sween, who said he had not felt “as human,” as he described, in a long time as he did when state lawmakers visited him and expressed solidarity with him.

Texas Senate Bill 1578, enacted in 2021, allows parents accused of child abuse by a medical professional to seek a second medical opinion from an independent doctor who specializes in the child’s specific medical condition. But Roberson did not benefit from this law, since it came nearly 20 years after his conviction.

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Sween also said Roberson’s case should raise concerns about capital punishment, even among people who support the death penalty, given the “really irrefutable evidence from experts with decades of experience pointing out the pneumonia in this child’s lungs.”

“If no court can hear that, and that is a reason then to kill somebody, I think it becomes hard to feel confident that Texas doesn’t frequently risk executing the innocent,” she said. “And I don’t know of anyone who would take the moral position that executing people for crimes that did not occur is somehow legitimate.”

As for Roberson’s mindset ahead of his scheduled execution, Sween said he seems to be fluctuating between being scared and being happy that people are concerned about the case.

“Every time he learns there are new people that care about the case, he gets this sort of childlike enthusiasm and feels hopeful again,” she said. “So it’s a kind of byproduct of his disability. And one of the things that I think helps him is that if you tell him, you know, we still have things to try and do, then he gets optimistic again. So he doesn’t go into complex philosophical thinking about this. He just doesn’t understand why he hasn’t already gone home.”