"This week, several current employees in your office -- including two who have agreed to go on the record -- informed the committee that your senior staff attempted to coerce them not to cooperate with the committee's inquiry and threatened their job and careers," Waxman wrote Friday in a letter to Krongard.
A spokeswoman said the IG's office has fully cooperated in the investigation but said she could not comment on the accuracy of the charges in the letter.
On Sept. 18, Waxman released a letter he wrote to Secretary of State Condoleezza Rice describing allegations by current and former employees in Krongard's office that the inspector general tried to shield the Bush administration from embarrassment by repeatedly shutting down investigations into fraud and abuse in Iraq and Afghanistan, as well as other irregularities.
Since the committee announced its investigations into those charges, officials under Krongard have improperly tried to dissuade other employees from cooperating with the committee, Waxman said Friday.
His latest letter says two officials -- Special Agent Ron Militana and Assistant Special Agent in Charge Brian Rubendall -- claim that in a Monday meeting, the IG's congressional liaison, Terry Heide, with an attorney from the office present, told them they could face retaliation based on their cooperation with the committee.
Heide allegedly advised them not to agree to voluntary interviews, Waxman said.
"You have no protection against reprisal. You have no whistleblower protections. Howard [Krongard] could retaliate and you would have no recourse," Heide allegedly said, based on Militana's notes, which he gave the committee. "Howard can fire you," Heide said later, according to the notes.
Though the meeting was supposed to be advisory, Waxman's letter says the investigators felt it was threatening. Waxman said other employees, who asked not to be identified because they feared retaliation, reported similar meetings.
An official familiar with the investigation said several employees involved have filed whistleblower disclosures with the independent Office of Special Counsel to ensure protection from retaliation. Waxman said the description of the meeting indicates officials may have violated civil and criminal laws against tampering with witnesses and retaliating against whistleblowers.
"The committee will not tolerate any intimidation of potential witnesses," Waxman wrote Friday.
"I direct you to instruct your staff, including your congressional affairs liaison and attorneys, to suspend all communications (other than those necessary to collect responsive documents) with employees the committee is planning to interview," he said. "I also warn you against any further efforts to intimidate witnesses or prevent truthful communications with Congress."