Texas is ready to execute Robert Roberson on Thursday despite strong evidence that he didn't shake his 2-year-old baby daughter to death in 2002, and a new subpoena of the inmate himself.

Shaken Baby Syndrome has since largely been debunked as "junk science" and no one has ever been executed for shaking a baby to death. Additionally, the lead detective in the case now says he got it wrong.

"Robert is a completely innocent man and we got it completely wrong, because we were looking for the wrong things," Brian Wharton, the former police detective who led the investigation and Roberson's arrest, told USA TODAY's The Excerpt podcast.

A bipartisan group of 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.” The board unanimously declined the recommendation on Wednesday. Hours later in an extraordinary move, the Texas Committee on Criminal Jurisprudence subpoenaed Roberson and scheduled a hearing for Monday − four days after the execution.

But it's unclear whether the subpoena will delay the execution. The Texas Department of Criminal Justice, which administers executions, told USA TODAY on Thursday that they were "aware of the subpoena and working with the Office of Attorney General on next steps."

When specifically asked if the execution remains scheduled, department spokeswoman Amanda Hernandez said: "At this time, TDCJ is preparing and planning to proceed as normal."

The Supreme Court or Republican Gov. Greg Abbott also could still intervene but Roberson has mere hours left before he's strapped to an execution table and given a lethal injection on Thursday.

Here's what you need to know about the execution.

What was Robert Roberson convicted of?

Roberson was convicted of killing his 2-year-old daughter Nikki in their home in the East Texas city of Palestine in 2002.

Roberson reported hearing Nikki cry and finding that she had fallen out of bed. After soothing her, he said they both went back to sleep. Later, when Roberson woke again, he found Nikki wasn’t breathing, and her lips had turned blue. At the emergency room, doctors observed symptoms consistent with brain death and she was pronounced dead the next day.

But Wharton told USA TODAY that Nikki had pneumonia in both lungs, pre-existing conditions for which she was prescribed opioids now banned for children, and undiagnosed sepsis. Wharton also said that his confirmation bias and a number of misunderstandings wrongly pointed him to Roberson's guilt.

For instance, 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.

"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."

What are the chances Robert Roberson's execution will be stopped?

The U.S. Supreme Court has been unpredictable when it comes to stays of execution but they are generally rare.

As for Abbott, he has overseen the execution of 76 inmates since he took office in 2015. He has granted clemency in only 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, unlike its recommendation against clemency for Roberson.

Abbott's office hasn't responded to multiple requests for comment from USA TODAY.

A number of Texas Republicans have urged mercy for Roberson and have been working to stop the execution, including Thursday's subpoena.

State Republican Rep. Jeff Leach wrote in a post on X that "we’re barreling towards an execution when a strong bipartisan majority of #txlege reps aren’t even sure a crime occurred — and are very sure due process didn’t.

“We have to do all we can to pump the brakes before this stains Texas justice for generations," he wrote.

When and where is Robert Roberson scheduled for execution?

Roberson is set to be executed sometime after 6 p.m. CT on Thursday, Oct. 17,  at the Texas State Penitentiary in Huntsville, just north of Houston.

If the execution he will be the nation's first inmate executed for Shaken Baby Syndrome. He will become the sixth inmate executed by Texas this year and either the 20th or the 21st in the nation, depending on whether he is pronounced dead before or after the simultaneous execution of Derrick Dearman in Alabama on Thursday.

What will Robert Roberson's last meal be if he's executed?

Roberson will choose his last meal from a menu available to all inmates at the prison since condemned inmates in Texas no longer make last meal requests.

Contributing: Taylor Wilson