The three-page letter sent Sunday by James Sullivan, Abbott’s general counsel, said only the governor has the constitutional authority to delay an execution. Sullivan warned that unless the court rejects the subpoena, “it can be repeated in every capital case, effectively rewriting the Constitution to reassign a power given only to the Governor.”

With his execution looming last Thursday, the 57-year-old Texas death row inmate watched as his attorneys’ legal arguments were rejected in the courts and his pleas for clemency disregarded, as the state parole board declined to recommend he receive a lesser sentence or reprieve.

Until Monday, the Texas governor had not publicly shared his thoughts on the actions of a bipartisan group of lawmakers that stopped Roberson's scheduled execution.

As the battle between the Texas House and the state's attorney general's office over the in-person testimony of inmate Robert Roberson continues, it opens the possibility of a new outcome from the Court of Criminal Appeals as one-third of the judges will not return to the bench.

After hearing more than nine hours of testimony Monday on Robert Roberson’s case, the House Criminal Jurisprudence Committee stood at ease – instead of adjourning – as lawmakers worked to get the death row inmate to appear in person in Austin.

Texas Governor Greg Abbott said that lawmakers stepped 'out of line' when intervening in the execution of Robert Roberson, who was scheduled to be executed last week

Robert Roberson was scheduled to be executed last Thursday for the 2002 killing of his 2-year-old daughter Nikki Curtis – who allegedly died from shaken baby syndrome.