Robert Roberson is to be executed in Texas in the unprecedented case of “shaken baby syndrome.”

Texas is scheduled to execute Robert Roberson III on Thursday evening. This could be an unprecedented execution of a disabled man convicted of killing his daughter based on verified scientific evidence.

Roberson, 57, was sentenced to death in 2003 for reportedly fatally shaking his 2-year-old daughter, Nikki. He is scheduled to be executed by lethal injection in Huntsville around 6 p.m.

If executed, Roberson, who is autistic, will be the first person in the country to be executed in a case of “shaken baby syndrome,” according to lawmakers.

Roberson has maintained his innocence on death row for more than two decades. His lawyers filed a series of last-minute pleas to stop his execution, arguing that the prosecution was based on “garbage science.” In a final attempt late Wednesday, a Texas House committee asked Roberson to testify at a hearing about how a state law that allows people to challenge convictions based on new scientific evidence was used in his case.

It was not immediately known whether the subpoena would impact Roberson’s execution.

“It is not shocking that the criminal justice system has failed Mr. Roberson so badly,” Gretchen Sween, one of Roberson’s attorneys, said in a statement The Dallas Morning News. “What is shocking is that the system has been unable to correct itself until now – when Texas lawmakers recognized the problem of wrongful convictions based on discredited ‘science’ over a decade ago.”

In 2002, when Roberson found Nikki unresponsive, he rushed her bruised, limp body to a Palestinian hospital, according to court documents. Roberson said she fell out of a bed, but medical staff suspected child abuse and called police about her injuries, which included bruises on her face, a bump on the back of her head and bleeding outside her brain. The cause of death was determined to be a blunt head injury.

The case against Roberson — who had just become Nikki’s sole caregiver — relied on doctors’ testimony that her death was consistent with “shaken baby syndrome,” in which an infant is seriously injured by violent shaking.

Cerebral hemorrhages were once considered one of several symptoms used to diagnose shaken baby syndrome. In the decades since Roberson’s conviction, research has found that these symptoms are not necessarily evidence of abuse.

Just last week, the Texas Court of Appeals overturned the conviction of a Dallas County man accused of harming a child because scientific advances undermined shaken baby syndrome. More than 30 people who served time in prison after convictions related to the theory have been declared innocent, according to the National Registry of Exonerations.

Roberson’s lawyers said new evidence shows that the chronically ill Nikki died of natural and accidental causes, including “severe, undiagnosed” pneumonia. According to court documents, she had a fever of 104.5 degrees days before her death; Her medical history included chronic infections that were not quenched by multiple strains of antibiotics and “alarming attacks of respiratory apnea.”

A coalition of bipartisan state lawmakers, best-selling author and Innocence Project board member John Grisham and a former Palestinian detective whose testimony helped convict Roberson have denounced his impending execution.

Detective Brian Wharton said he believes Roberson is innocent. Despite receiving Roberson’s forgiveness, Wharton said he will be “forever haunted” for his role in his arrest and prosecution.

“We rushed to judgment,” Wharton wrote in a letter to the state’s parole board. “We were wrong, the jury was misinformed and Robert is not guilty of any crime. If we are truly a nation of laws, a people who love justice in the truest sense of the word, then Robert Leslie Roberson III must be released.”

The parole board on Wednesday recommended no clemency for Roberson, who had asked to commute his death sentence or delay execution for 180 days.

An Anderson County judge on Tuesday rejected arguments from Roberson’s lawyers that his death sentence was unlawful because the judge who oversaw the post-conviction proceedings made an error.

The state’s highest criminal appeals court has also repeatedly refused to take action against Roberson’s death sentence.

Roberson would be the sixth person to be executed in Texas this year. Texas has led the nation in executions since reinstating the death penalty in 1976. Eight people were executed in the state in 2023.