Roberson remains scheduled to die by lethal injection despite evidence indicating he was wrongfully convicted for the death of his 2-year-old daughter Nikki, whom police believed was shaken to death.

What happens to a man on death row when the lead detective in his case says he got it wrong, that he’s convinced of the inmate's innocence, and has been begging for the courts, for the governor – anyone – to save that man's life?

In Texas so far, nothing.

Robert Leslie Roberson remains scheduled to die by lethal injection on Thursday despite all evidence indicating he was wrongfully convicted for the death of his 2-year-old daughter, Nikki, in 2002. At the time, investigators saw what they wanted to see: shaken baby syndrome. In reality, little Nikki had pneumonia in both lungs, she had pre-existing conditions for which she was prescribed opioids that are now banned for children, and she had undiagnosed sepsis.

That's according to Brian Wharton, the former police detective who led the investigation and subsequent arrest of Roberson. Wharton, now an ordained minister in the United Methodist Church, spoke with USA TODAY's The Excerpt podcast in a candid conversation about errors in the case and what should be the proper course for Texas.

"I was wrong. I didn't see Robert. I did not hear Robert," Wharton said. "I can tell you now, he is a good man. He is a kind man. He is a gracious man. And he did not do what the state of Texas and I have accused him of."

Is it possible investigators got it wrong?

Wharton explained that a number of misunderstandings and confirmation bias led him to believe Roberson killed his daughter.

For one, when Roberson brought Nikki to the hospital, nurses, doctors and investigators observed that he seemed to be devoid of emotion, something Wharton looked at as a red flag at the time but now understands as behavior associated with people who are autistic, like Roberson.

Wharton also described the heightened emotion in the hospital as doctors worked frantically to save Nikki's life.

"That emotional charge in the hospital that here is a 2-year-old little girl that is about to die, somebody did this to her, who did it, how did it happen?" Wharton said. "And the first thing you hear is abuse, shaken baby syndrome, and we just take it and run with it, and we find all the facts that we need to make it stand up."

So, investigators dismissed Wharton's explanation that among Nikki's other medical problems, she had fallen from her bed that night.

But make no mistake, Wharton said: "Robert is a completely innocent man and we got it completely wrong, because we were looking for the wrong things."

Others demanding Robert Roberson's execution be stopped

A cacophony of voices is demanding Roberson's execution be stopped, most notably a body that typically wholeheartedly supports the death penalty.

Last month, a bipartisan group of 84 Texas lawmakers urged the state's Board of Pardons and Paroles to recommend clemency for Roberson "out of grave concern that Texas may put him to death for a crime that did not occur.”

“It should shock all Texans that we are barreling towards an execution in the face of this new evidence,” wrote the Texas Legislature members. “Other states look to Texas as a leader for both enforcing the rule of law and addressing wrongful convictions. We now look to you to prevent our state from tarnishing that reputation by allowing this execution to proceed.”

Additionally, 34 scientific and medical experts wrote to the board explaining that had Nikki died today, "no doctor would consider Shaken Baby Syndrome" as the cause because the condition "is now considered a diagnosis of exclusion."

"Nikki’s pneumonia, the extreme levels of dangerous medications found in her system during her autopsy, and her fall from the bed explain why Nikki died," the experts wrote.

Also calling for Roberson's salvation: groups representing parental rights, autism advocates, faith leaders and anti-death penalty groups including the Innocence Project, and bestselling author John Grisham.

"Nikki’s death was a tragedy, not a crime," Grisham wrote in a column for the Palestine Herald-Press. "Robert Roberson may be out of options unless Texas authorities recognize the injustice of Mr. Robertson’s conviction and death sentence, reverse course, and grant him a new trial."

What will it take to stop Robert Roberson's execution?

The Texas Board of Pardons and Paroles was weighing whether to recommend clemency for Roberson, and Republican Gov. Greg Abbott could intervene.

Abbott has referred to the death penalty as "Texas justice" and has overseen the execution of 76 inmates since he took office in 2015. He has granted clemency in one of those cases, that of Thomas Whitaker, whose sentence Abbott commuted to life in prison in early 2018, just minutes before he was scheduled to be executed for masterminding the fatal shootings of his mother and brother. The parole board had unanimously recommended clemency.

Abbott's office didn't respond to USA TODAY's request for comment.

The U.S. Supreme Court could also stop Roberson's execution, but perhaps his biggest hope for reprieve rests with the Texas House Committee on Criminal Jurisprudence. A bipartisan group of lawmakers with the committee rushed to schedule a hearing for Wednesday on whether to invoke a state law banning the death penalty for convictions based on junk science, reported the Austin-American Statesman, part of the USA TODAY Network.

State Republican Rep. Jeff Leach wrote in a social media post on Friday, “We have to do all we can to pump the brakes before this stains Texas justice for generations.”

If Robert Roberson's execution moves forward ...

If Roberson's execution moves forward, he would become the first person to be executed in connection with shaken baby syndrome, considered junk science by many in the scientific community.

Roberson, 57, also would become the sixth inmate put to death this year in Texas, by far the nation's most prolific state when it comes to the death penalty. The state has executed 590 inmates, the most of any state, followed by Oklahoma at 126.

Roberson also would become the 20th inmate executed in the U.S. in 2024. Another eight are scheduled and more could be added by the end of the year.

Roberson's execution is scheduled not only on the same day but at the same time as that of Alabama inmate Derrick Dearman, who has long admitted to killing five people, including a pregnant woman, with an ax and a gun in an attack fueled by anger at his then-girlfriend in 2016.

Contributing: John C. Moritz, Bayliss Wagner