(CNN) -- The ex-wife of a Texas convict executed in 2004 for the deaths of his three children reaffirmed her belief in his guilt Wednesday as his relatives sought to open a new inquiry into the case.
The family of Cameron Todd Willingham has asked a judge to posthumously clear his name, arguing that he was put to death based on "junk science." Though Willingham was executed in 2004 for killing his three daughters by setting fire to his house, subsequent investigations by outside experts have concluded that the fire that killed the girls should not have been ruled arson.
Willingham's ex-wife, Stacy Kuykendall, has kept a low profile throughout the debate over his execution. But she told reporters outside the Travis County courthouse in Austin that "I am here to make sure that my daughters' voices are heard."
"Todd murdered Amber, Karmon and Kameron. He burnt them," she said. "He admitted he burnt them to me, and he was convicted for his crime. That is the closest to justice that my daughters will ever get."
Kuykendall spoke before an Austin judge opened a hearing into the Willingham's family's request for an inquiry into the execution. But inside the courtroom, prosecutors from the town of Corsicana -- where the 1991 fire took place -- forced a delay in the proceedings by challenging the impartiality of District Judge Charlie Baird and asking him to recuse himself.
Baird told lawyers he will issue a decision on that request next week, said Gerry Goldstein, a lawyer representing Willingham's stepmother, Eugenia Willingham, and cousin Patricia Cox.
Goldstein pointed out that Kuykendall has told differing stories about whether her former husband ever admitted his guilt in the fatal fire, and criticized death-penalty supporters for "parading her on the courthouse steps while they're inside trying to stop proceedings."
"What possible harm could there be to their side to have this aired in court?" he asked.
Also representing the family is The Innocence Project, led by nationally known defense lawyer Barry Scheck. Lowell Thompson, the district attorney for Navarro County, which includes Corsicana, did not return a phone call seeking comment Wednesday.
In asking Baird to open a "court of inquiry" into the execution, Willingham's family argues that he was put to death for a crime "that modern science reveals may never have been committed." State officials failed to act on evidence of "significant deficiencies" in the finding of arson at the heart of the case before the execution, and have "continued to resist attempts to clear Mr. Willingham's name," their petition states.
"If we can get a hearing before him or any other fair judge, we're going to go ahead," Goldstein said.
The Texas Forensic Science Commission is investigating claims that state fire marshals ruled the fatal blaze arson based on outdated or faulty science. The first of three reports to reach that conclusion was sent to Gov. Rick Perry's office and submitted to appeals courts before Willingham's execution, while two others were conducted after his death.
"Despite overwhelming scientific evidence, state officials have continued to demonize Mr. Willingham and defend the arson evidence on which he and others have been convicted," the family's petition states.
The Forensic Science Commission was to hear from the author of the most recent of those reports in October 2009. But the panel's deliberations were put off after Perry -- who allowed the execution to go forward -- abruptly shook up the panel, spurring complaints from the Willingham family and allegations that Perry was trying to head off the potential admission that Texas had put an innocent man to death.
In July, the commission found that arson investigators used flawed science but were not negligent and did not commit misconduct.
A spokeswoman for the governor's office told CNN on Tuesday that Perry, who allowed the execution to go forward, remains convinced of Willingham's guilt. And Corsicana authorities have said that evidence beyond the testimony of state fire marshals supported Willingham's conviction.
CNN's Emanuella Grinberg contributed to this report.