Current and former employees of Cobb's office alleged that he suppressed investigations within NASA and penalized his own investigators when they pursued cases, the Post reported on its Web site Thursday night.
At least 16 people provided documents and written complaints about Cobb to the Integrity Committee of the President's Council on Integrity and Efficiency, a group charged with investigating misconduct by agency inspectors general or their staffs, the Post said.
According to the complaints described by the Post, Cobb hampered investigations into problems such as a malfunctioning self-destruct procedure during a space shuttle launch and the theft of data on rocket engines.
Cobb would not discuss the case with the Post but said, "The office has been particularly dedicated to ensuring an atmosphere where safety concerns are fully addressed."
Last April, The Daily Press of Newport News, Va., reported on allegations that Cobb had retaliated against NASA research pilot Robert Rivers in a dispute over aircraft safety.
Sen. Bill Nelson, D-Fla., forwarded the article to NASA Administrator Michael D. Griffin, the Post reported, and throughout 2005, Nelson's office gathered information from Cobb's current and former subordinates.
"We sent information from probably more than a dozen current or former employees to the integrity council," Nelson spokesman Dan McLaughlin said in a telephone interview early Friday. "Senator Nelson received a letter from the integrity council notifying him that they would be conducting an investigation."
McLaughlin would not disclose the nature of the allegations made by the current and former employees.
Dan Samoviski, who retired in 2004 as deputy IG director for audits at NASA headquarters, told the Post, "Personally, I just think he created a hostile work environment."
Several sources also told the Post that Cobb suppressed audits and stopped investigations to avoid embarrassing NASA or its leadership.
Chris Swecker, assistant director of the FBI's criminal investigative division, leads the Integrity Committee. It also includes the head of the Office of Special Counsel, the director of the Office of Government Ethics and several sitting inspectors general.
FBI officials did not immediately return phone messages late Thursday night.