(CNN) -- An anthrax victim's widow said new evidence about the suspect in the 2001 attacks released to the public supports her $50 million lawsuit blaming the federal government for her husband's death.
Maureen Stevens said the evidence that the Justice Department said links Army biological researcher Bruce Ivins to the anthrax attacks proves her claim that the government's lack of security allowed a mentally unstable man access to "some of the deadliest substances known to mankind."
The U.S. government Wednesday declared Ivins the lone culprit in the anthrax attacks, saying he had a history of mental illness, and that he created and mailed the spores used to kill five people.
Authorities say Ivins, a 62-year-old Army biodefense researcher at the U.S. Army Medical Research Institute for Infectious Diseases in Frederick, Maryland, committed suicide last week as they were preparing to charge him with carrying out the anthrax attacks.
In a statement Wednesday, Ivins' attorneys said the scientist was innocent and the stack of documents the government released to support its conclusion fell short of "concrete evidence."
Stevens' husband, Bob, 63, was the first victim of the attacks that terrorized the nation shortly after 9/11.
"We have now been advised that the man the FBI believes perpetrated this heinous act had a history of mental instability of long standing, and yet he was allowed to work with anthrax and some of the most deadly substances known to mankind," Maureen Stevens said, reading from a prepared statement with her attorney by her side.
Federal attorneys have tried to get the lawsuit dismissed, arguing that if a government employee were found to be the suspect, it is beyond an employment issue and the government isn't culpable.
Dean Boyd, spokesman for the U.S. Justice Department, said Thursday that he could not comment on any pending litigation.
"The United States denies as a matter of law and fact that the plaintiff is entitled to the relief sought," a government court filing in the suit said.
But in the suit, Stevens contends the government "owed a duty of care, the highest degree of care" in checking and supervising those who had access to and handled anthrax.
Stevens said she hopes her wrongful death lawsuit, filed in 2003, will be settled soon with the government in light of the new developments.
"[Ivins was] allowed to examine evidence and participate in the investigation of the very crime he committed," she said. "To us, my family, this is shocking."
She said the evidence supports her position, stated in the lawsuit, that the crime was committed by a "United States government insider with the access and ability to get this substance out of the Fort Detrick [Maryland] lab, as a result of poor or nonexistent security."
"Our view has proven to be correct," she said. "It is now time for the United States of America to own up to its responsibilities to my family and to right this wrong that resulted in the loss of my beloved husband and my children's beloved father."
Stevens said she learned the government named Ivins as its suspect through the media. After talking with the FBI, she said she is 100 percent positive that Ivins was the man who killed her husband.
Bob Stevens, a tabloid photo editor, died in October 2001 after inhaling anthrax that investigators believe was in a letter sent to American Media Inc., the publisher of the Sun and National Enquirer, at its offices in Boca Raton, Florida.