HOUSTON (AP) — Robert Roberson, set to be the first person in the U.S. to be put to death for a murder conviction tied to a diagnosis of shaken baby syndrome, was nearly out of options to stop his execution in Texas.

A state parole board, multiple lower courts and the U.S. Supreme Court had all rejected his requests to delay his lethal injection on Thursday evening for the killing of his 2-year-old daughter in 2002. And it seemed unlikely that Texas Gov. Greg Abbott would use his power to grant a one-time 30-day reprieve as he had only stopped one imminent execution in his nearly 10 years in office.

Roberson’s final hope rested with a bipartisan group of Texas lawmakers who believe he is innocent and their extraordinary and unprecedented strategy to delay his execution: issuing a subpoena for him to testify before a House committee next week, which would be days after he was scheduled to die.

After several hours of legal debate Thursday evening among three different state courts, the Texas Supreme Court sided with the lawmakers and upheld a temporary restraining order that stayed the execution.

The unconventional method of using a subpoena to stop Roberson’s execution was punctuated by the delay coming from the Texas Supreme Court, the state’s highest civil court. Amy Starnes, a court spokesperson, said the Texas Supreme Court's chief justice wasn't aware of another execution that had been stopped by the court.

“It really is highly dramatic and something I certainly have never seen,” said Sandra Guerra Thompson, a law professor at the University of Houston Law Center.

Roberson is now set to speak in person before the Texas House Criminal Jurisprudence Committee on Monday. But beyond that, it is unclear what will happen in his case. A new execution date could be set. Roberson’s attorneys say they will use the extra time he has to fight for a new trial.

Here’s what to know about Roberson’s case and how his execution was delayed:

What was Roberson convicted of doing?

Roberson, 57, was convicted of killing his daughter, Nikki Curtis, in the East Texas city of Palestine. Authorities say Curtis died from injuries related to shaken baby syndrome. Roberson’s lawyers and some medical experts say his daughter died not from abuse but from complications related to pneumonia. They say his conviction was based on flawed and now outdated scientific evidence.

The diagnosis of shaken baby syndrome refers to a serious brain injury caused when a child’s head is hurt through shaking or some other violent impact, like being slammed against a wall or thrown on the floor.

Roberson’s supporters don’t deny head and other injuries from child abuse are real. But they say doctors misdiagnosed Curtis’ injuries as being related to shaken baby syndrome and that new evidence has shown the girl died from complications related to severe pneumonia.

Anderson County District Attorney Allyson Mitchell has said the prosecution’s case showed the girl had been abused by her father.

How did Texas House committee try to stop the execution?

Texas House Criminal Jurisprudence Committee late Wednesday decided to issue a subpoena for Roberson as a way of delaying his execution.

“This was the one of the few avenues open to them was the subpoena power that that they have,” Thompson said.

The committee’s members argued before a judge in Austin on Thursday, less than two hours before Roberson’s scheduled execution, that they needed to hear from Roberson about whether a 2013 law created to allow prisoners to challenge their convictions based on new scientific evidence was ignored in his case.

The judge sided with the lawmakers and issued a temporary restraining order that would essentially delay the execution. The order came as the U.S. Supreme Court rejected Roberson’s request to stay his execution.

The judge's order was appealed by the state to the Texas Court of Criminal Appeals, the state’s top criminal court, which overturned it. The lawmakers had one final move: an appeal to the Texas Supreme Court.

Thompson said the lawmakers were able to ask the Texas Supreme Court to step in because laws regarding subpoenas are civil in nature.

“I think it’s extremely unusual, but not likely to become a regular occurrence,” Thompson said.

In its ruling, the Texas Supreme Court said while it has no authority over criminal cases, the questions being raised over whether the Legislature can use its authority to compel a witness to testify and as a result block the enforcement of a death sentence is a matter of civil law that will have to be decided.

“While the news from the Supreme Court is encouraging, we cannot stop advocating for Robert because of this temporary win. Despite the extraordinary efforts of our elected officials, his attorneys, medical experts and the hundreds of thousands of people who spoke out for Robert, his fate is far from certain,” the Innocence Project, which is working with Roberson’s legal team, said in a statement.

What happens next?

Roberson is scheduled to testify in person before the Texas House committee on Monday, said Gretchen Sween, one of Roberson’s attorneys.

Once he appears before the committee, that fulfills the subpoena and there is nothing to prevent the setting of another execution date, Thompson said.

Mitchell, the district attorney in Anderson County, could seek a new execution date at any time after Monday’s hearing, Sween said.

Mitchell did not immediately reply to an email seeking comment.

But under Texas law, a new execution could not take place until about 90 days after a judge sets a new date. The earliest a new execution could be set would be in 2025, Sween said.

“We will continue to seek out avenues to get relief for Robert in the form of a new trial. But the only obvious way that can happen at this time is through the (Texas Court of Criminal Appeals), which has not yet been inclined to look at the new evidence,” Sween said in an email.

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Follow Juan A. Lozano on X at https://x.com/juanlozano70.