A decade after anthrax attacks killed five people in the United States and sickened 17 others, an LSU scientist and two other experts are questioning the FBI’s conclusion that a lone researcher in Maryland was responsible.

“We’re saying the spores are not likely to have been produced at Fort Detrick,” said Martin E. Hugh-Jones, professor emeritus at LSU’s School of the Coast & Environment.

Hugh-Jones, New York biologist Barbara Hatch Rosenberg and Texas chemist Stuart Jacobsen have written a paper on the subject for the Journal of Bioterrorism & Biodefense.

The FBI concluded that lethal letters containing anthrax powder in 2001 were the work of Bruce Ivins, a researcher at the Army Medical Research Institute of Infectious Diseases at Fort Detrick in Frederick, Md.

Ivins, however, committed suicide in 2008 while federal prosecutors were preparing a criminal case against him.

Justice Department officials in Washington, D.C., could not be reached Monday, a federal holiday — Columbus Day.

But the woman who would have been the federal government’s lead prosecutor was quoted in a national story for Tuesday as saying she does not doubt Ivins’ guilt.

That story was prepared by writers for ProPublica, McClatchy Newspapers and PBS’ Frontline.

Rachel Lieber, the federal prosecutor, was quoted as saying a jury would have convicted Ivins of the murders.

“You can get into the weeds, and you can take little shots of each of these aspects of our vast … mosaic of evidence against Dr. Ivins,” Lieber was quoted as saying.

“And ladies and gentlemen, the big picture is, you have … brick upon brick upon brick upon brick upon brick of a wall of evidence that demonstrates that Dr. Ivins was guilty of this offense,” Lieber was quoted by the team of reporters.

“I’ve always doubted it,” LSU’s Hugh-Jones said of the allegation against Ivins. “I knew Bruce for years. It was not the sort of thing he would do.”

Hugh-Jones said he listened to several of Ivins’ research colleagues at his memorial service.

“They didn’t believe it,” Hugh-Jones said of the allegation against Ivins. “Not at all.

“The FBI got it wrong,” Hugh-Jones added. “They should go back and look again, and do it right this time. They were out of their depth on this one.”

The longtime anthrax researcher said federal agents should have investigated all U.S. anthrax research laboratories. Invoices should have been checked for purchases of the ingredients necessary for production of anthrax spores. Inventories should have been checked to see whether any materials could not be accounted for.

“That’s the thing that jumped out at us,” said Hugh-Jones. “And we used the FBI’s data. Somebody must have been asleep.”

Hugh-Jones added that evidence of rapid improvements in quality control were visible in the letters used to spread the deadly powder.

The first contained debris that lessened the quality of the spores, the LSU scientist said. The second letter was free of that debris, he added.

“That tells me it was part of some research program,” Hugh-Jones said.

“What stuck out like a sore thumb was the tin,” in the powdered anthrax, he said.

“When you add the tin … it makes the anthrax much stronger, structurally stronger,” Hugh-Jones added.

The killer or killers also combined the tin and anthrax in a microencapsulation process that further strengthened the poison, Hugh-Jones said.

It took expert cleaning crews two months to decontaminate a Florida office building where one man was fatally poisoned, the LSU researcher noted.

“Making these encapsulated spores is not very straightforward,” Hugh-Jones said.

“It’s complicated,” he said. “This was probably part of a research program somewhere, and someone took advantage of it.”

Early in the anthrax investigation, the Justice Department publicly identified former Army microbiologist Steven Hatfill as a “person of interest.”

LSU had hired Hatfill as director of its National Center for Biomedical Research and Training. But the school fired Hatfill in 2003, after the Justice Department’s announcement.

Hatfill was not prosecuted. He eventually received a $5.8 million settlement from the Justice Department.