There’s been yet another blow to the case against Cameron Todd Willingham, the Texas man who was executed in 2004 for setting a fire that killed his three young daughters at their home.

This month, the State Bar of Texas formally accused the lead prosecutor of misconduct after an investigation requested by the Innocence Project. The filing, first reported by The Marshall Project, said that John H. Jackson knew about evidence that bolstered the case for Willingham’s innocence and kept it from his attorney.

“Before, during and after the 1992 trial, [Jackson] knew of the existence of evidence that tended to negate the guilt of Willingham and failed to disclose that evidence to defense counsel,” the bar said.

Specifically, the bar said that Jackson kept quiet about a deal he struck with his star witness: a prisoner named Johnny Webb, who testified that Willingham told him he had started the fire. Up until his death, Willingham had always maintained his innocence.

Webb recanted his statements about Willingham in 2000 and again last year, saying that Jackson encouraged him to lie on the stand in exchange for a shorter sentence and a prison transfer. Webb, who was facing a long sentence for robbery, said the prosecutor had convinced him that Willingham was guilty. He took the deal. As The Washington Post and The Marshall Project reported:

“‘Your story doesn’t have to match exactly’,” Webb said Jackson told him. “He says, ‘I want you to just say he put fires in the corners. I need you to be able to say that so we can convict him, otherwise we’re going to have a murderer running our streets.’”

In fact, Webb said, Willingham “never told me nothing.”

In its grievance, the bar said that Jackson intervened to help Webb, reducing his aggravated robbery conviction, requesting early parole and transferring him from prison to serve his time in the county jail.

Jackson has repeatedly denied any wrongdoing to The Marshall Project and in court documents. He has admitted to helping transfer Webb, but only because, he said, Webb was being threatened for his testimony in prison.

Jackson’s lawyer told The Marshall Project that he would ask a jury to hear the accusations against Jackson, in accordance with state bar rules.

Watch Now: Death by Fire

Death by Fire examines Webb’s testimony and raises additional questions about the evidence used to convict Cameron Todd Willingham, in particular investigators’ reliance on an outdated understanding of the science in arson cases.

Sarah Childress, Former Series Senior Editor, FRONTLINE