Advocates were fighting for a Texas mans life on Wednesday just hours before his scheduled execution in the death of his 2-year-old daughter, who prosecutors had argued was killed under the disputed cause known as shaken baby syndrome.

The Texas Board of Pardons and Parole voted Wednesday against supporting clemency for 57-year-old Robert Roberson, who has spent more than 20 years on death row after being found guilty in 2003 of the murder of his daughter Nikki Curtis. Roberson is scheduled to be executed Thursday evening and would be the first person executed in a case involving the cause-of-death ruling, which a number of experts including the neurosurgeon who first described the syndrome in a research paper say has been misused in the criminal justice system to put innocent people behind bars .

A clemency board document obtained by HuffPost revealed all six parole board members voted against recommending commuting Robersons death sentence to a lesser penalty or granting him a 180-day reprieve of his execution. The matter is now in Texas Gov. Greg Abbotts hands.

Robersons lawyers and medical experts who are supporting him are not arguing whether children die of abusive shaking but rather that doctors misdiagnosed Nikkis injuries. Prosecutors did not consider other causes for her death at trial, and new evidence indicates the girl died of symptoms related to pneumonia, Robersons supporters said.

Following the parole boards recommendation, Robersons attorney Gretchen Sween called for Abbott to grant a 30-day reprieve on the execution for a court to hear the overwhelming new evidence. She also questioned why a Texas state law allowing prisoners to challenge convictions based on junk science hasnt been invoked to grant Roberson a new trial.

We pray that Governor Abbott does everything in his power to prevent the tragic, irreversible mistake of executing an innocent man, she said in a statement.

In the weeks leading up to her death, Nikki had suffered from a respiratory infection, vomiting and diarrhea, according to a motion by Robersons attorneys . Roberson, who lived in Palestine, a small town in East Texas, rushed his daughter to the local emergency room on Jan. 28, 2002, and she developed a 104.5 fever the following day.