Washington ? The State Department’s embattled inspector general, accused of impeding a Justice Department investigation of Blackwater Worldwide, announced his resignation Friday, saying a poisonous political atmosphere in Washington deters people from careers in public service.

Howard Krongard told President Bush in a letter that he would quit effective Jan. 15. He released a brief public statement that said recent congressional testimony and correspondence gives ample documentation of the reasons for his departure. He listed, in Washington-style bullet points, the dates of his previous statements dealing with conflict-of-interest and other allegations.

“I have nothing further to say at this time,” he wrote.

Krongard has said he never stood in the way of the Blackwater probe, and he and his attorney have said he did not know his brother was a Blackwater adviser. A letter from his attorney, who has called the situation “he-said, he-said,” is one of the documents Krongard lists in his statement.

In his letter to Bush, a frustrated Krongard pointed to what he called structural problems with the way the State Department inspector job is set up.

“Of even greater concern to me is the grave threat to public service posed by the current rancor and distrust” in Washington, Krongard said.

He singled out the political parties, feuding branches of government, the media and interest groups.

“We thank him for his service,” said State Department spokesman Gonzalo Gallegos.

Blackwater Worldwide – a private contractor that protects U.S. diplomats in Iraq – is alleged to have smuggled weapons into the country. In November, Krongard was forced to recuse himself from any inquiries into Blackwater after it was disclosed that his brother had joined the company’s advisory board.

In addition to recusing himself from matters related to Blackwater, Krongard also said last month he was no longer involved in corruption investigations related to the flawed construction of the U.S. Embassy in Baghdad, a $600 million project that is beset by logistical delays and security concerns.

Howard Krongard’s brother, Alvin, quit as an adviser to Blackwater two days after his relationship with the security contractor was sharply criticized by the House Oversight and Government Reform Committee.

Blackwater is a major State Department contractor and the subject of ongoing federal investigations. One of those is examining whether Blackwater guards violated use-of-force rules during a Sept. 16 shooting in Baghdad that left 17 Iraqis dead.

Krongard is the second high-ranking State Department official to leave in the wake of the Blackwater scandal and as Secretary of State Condoleezza Rice has faced congressional criticism of mismanagement.

In late October, Rice ousted the State Department’s security chief, Richard Griffin, after a review panel she convened found serious deficiencies in his office’s oversight of private contractors in Iraq.