Former first lady Margarita Zavala has hit back at the chief justice of the Supreme Court (SCJN) after he accused the government of ex-president Felipe Calderón of improper conduct in relation to a fire at a daycare center in Sonora in 2009 that claimed the lives of 49 children.

Presenting his new book on Tuesday, Chief Justice Arturo Zaldívar claimed there was “an operation by the state to protect the family of the president’s wife [and] to protect the high-ranking officials of that government” from being accused of wrongdoing in connection with the fire at the ABC Daycare Center in Hermosillo in June 2009.

He asserted that the 2006-12 Calderón administration pressured the SCJN to hand down rulings that were not unfavorable to the government.

Numerous officials with the Mexican Social Security Institute, Civil Protection and other government departments were eventually found criminally responsible for the deaths of the children and sentenced to lengthy jail terms.

Zaldívar, appointed to the SCJN by Calderón in 2009 but now considered an ally of President López Obrador, said he had a heated, hours-long discussion with former interior minister Fernando Gómez-Mont about the court’s consideration of the daycare center case.

He said he directed Calderón’s interior minister to “tell the president that he nominated a justice” and hadn’t appointed a “minister of the state.”

“I’m not his employee and I won’t carry the death of 49 children on my conscience,” Zaldívar recalled telling Gómez-Mont.

In addition, the chief justice claimed that the Calderón government didn’t allow children injured in the fire to be airlifted to a hospital that was waiting for them in Sacramento, United States, “because they didn’t want the scandal to become a big one.”

Zavala, currently a federal deputy for the National Action Party, accused Zaldívar of lying in a series of Twitter posts published Wednesday.

“He’s lying by saying there was an operation to protect my family,” she said in one post, adding that the federal government obtained a warrant for the arrest of one of her relatives.

“Zaldívar is lying because it was precisely the federal government that arranged for children to go to specialist hospitals in the United States,” Zavala wrote in another post.

She also said that she is still in contact with some of the mothers who lost their children in the 2009 tragedy.

“None of what he said yesterday appears in his book, … it just occurred to him at the time [he was presenting it]. Don’t come up with any more bright ideas @ArturoZaldivarL and concentrate on your work, which is justice in Mexico, and what little you’ve done for that in these years,” Zavala said.

In an interview Wednesday night, the chief justice responded that everything he said on Tuesday “is proven.”

Calderón hasn’t personally responded to Zaldívar’s claims but he has retweeted the opinions of several other people.

“Frankly, @ArturoZaldivarL has lost all credibility,” said one of the Twitter posts republished by the ex-president.

With reports from El Universal