This story was co-published with PBS Frontline and McClatchy.

WASHINGTON -- Rushing into court to undo a major blunder, Justice Department lawyers defending a civil suit Tuesday retracted statements that question the FBI's finding that a former Army microbiologist mailed the anthrax-filled letters that killed five people in 2001.

But the unusual seven-page correction, filed in federal court in Florida, does not erase testimony from government scientists who challenged the FBI's finding that the late Bruce Ivins was the perpetrator.

The department's legal dance stems from its two seemingly conflicting roles: backing up the FBI's finding that Ivins, who committed suicide in July 2008, was the killer; and defending an Army bio-weapons lab at Fort Detrick, Md., against allegations of negligence.

The department's Civil Division is attempting to limit federal liability over the death of the first anthrax victim, a Boca Raton, Fla., man whose family is seeking $50 million in damages for alleged negligence by the lab at the U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID), where Ivins worked on anthrax vaccines.

In trying to minimize USAMRIID's liability, government lawyers have had to walk a fine line, because the FBI says Ivins produced the anthrax powder at the facility while the civil lawyers seemed to suggest it could have been prepared elsewhere.

Tuesday's retraction came a day after a collaborative report by McClatchy, the Public Broadcasting System's Frontline news magazine and ProPublica, disclosing what appeared to be an explosive Justice Department revelation.

In a legal filing last week, department lawyers in the civil case said that the lab lacked the "specialized equipment in a containment suite" needed for Ivins to have dried the deadly powder.

That and other statements raised hackles at the FBI and among prosecutors in the criminal case, leading to hurried huddles at the Justice Department.

In a statement Tuesday, department spokesman Dean Boyd said that Civil Division lawyers had submitted "inaccurate information" and that "the Justice Department and FBI stand behind their findings that Dr. Ivins had the necessary equipment in the containment suite" to produce the spores.

They noted that Ivins had ordered his own machine, known as a lyophilizer, that could be used for drying anthrax spores. The machine was labeled "property of Bruce Ivins" and was located in a nearby biocontainment suite.

Although it amended the filing, the Justice Department could not take back what government scientists had said in sworn depositions.

Stephen Little, a technician at the Army lab, was asked whether the equipment could have been used to make the dried spore preparation used in the letters.

"Not any equipment I have seen," Little replied.

Little said that there was "no way" Ivins could have moved the lyophilizer to the into the biocontainment suite, where Ivins' lab space was located.

"The thing is as big as a refrigerator," Little said.

Another scientist, Susan Welkos, said, "We don't have any way to produce the massive amount of (anthrax) material that would have been necessary to grow up and dry in a way that wouldn't have killed everybody in the institute."

Both quotations were highlighted by Justice Department lawyers in their submission to the court last week.

Friday's filing also said that Ivins sent anthrax from a flask in his lab—a flask that the FBI contends provided the parent material for the letter anthrax—to two outside laboratories, the Battelle Memorial Institute in West Jefferson, Ohio, and a lab operated by BioPort in Lansing, Mich.

The amended filing said that Ivins sent the spores only to Battelle, narrowing the number of parties who might have been considered suspects.

Boyd said that the department and the FBI "have never wavered from that view that Dr. Ivins mailed the anthrax letters."

Ivins overdosed on Tylenol and two other drugs not long after learning that federal prosecutors were preparing to indict him on capital murder charges.

It was unclear how the court filings by the Civil Division ended up so at odds with the narrative developed by prosecutors, and the department did not offer an explanation.