Scientists are stepping up among those most skeptical of the FBI's evidence implicating military microbiologist Bruce Ivins in the 2001 Anthrax attacks.

In yesterday's New York Times, microbiologist Gerry Andrews wrote an op-ed describing himself as "both disheartened and perplexed by the lack of physical evidence" against Ivins. Andrews worked with Ivins for 16 years and served as the chief of the bacteriology division at the military lab at Ft. Detrick in Maryland.

While the FBI last week released extensive documents with circumstantial evidence against Ivins, they provided almost no details of the scientific testing that underpinned the investigation.

While questions about scientific aspects of the case have been aired, they are often relegated to the bottom of news stories behind other aspects of the investigation, such as Ivins' emails around the time of the attacks or his mental problems.

Today Dr. Meryl Nass, a bioweapons expert, rattled off a long list of concerns about the case on her blog.

Editors at Science Blogs built on their initial skepticism by publishing an additional piece titled "Anthrax Case: Reasonable Doubt on the Science."

The American Society of Microbiologists, the primary professional association for the field, has not issued any public statements on the case, but is prepared to provide experts for testimony on Capitol Hill if asked, spokeswoman Barbara Hyde told TPMmuckraker.

Meanwhile, virtually nobody with a science background in microbiology has stepped forward in support of the FBI's conclusion that Ivins was likely the one and only person involved in the 2001 attacks, said Gigi Gronvall, a senior associate with the Center for Biosecurity at the University of Pittsburgh Medical Center.

"[Federal officials] came out and said they'd made the case, but they didn't actually present that science. So it really can't be evaluated," Gronvall said in an interview. "They talked about the genetic signature but they didn't elaborate on what that was. We want to know how they were able to determine that that one flask contained the parent train of what was sent out."