State Department Inspector General Howard J. Krongard, who has been accused of improperly interfering with investigations into private security contractor Blackwater USA and with other probes, resigned Friday.

In a brief public statement, the longtime corporate lawyer pointed to his recent battles with congressional Democrats and said they explained the reason for his departure.

“I have nothing further to say at this time,” wrote Krongard, whose job made him the department’s chief internal watchdog.

In a separate resignation letter to President Bush, he said that he was troubled by “inherent structural and conceptual defects” in the inspector general’s job.

He also expressed concern about the “grave threat to public service posed by current rancor and distrust” among political parties, the government, the media and interest groups.

Krongard, 66, has been accused by current and former members of his staff and by congressional Democrats of thwarting investigations of waste and fraud in Iraq. Among those are allegations of arms smuggling by Blackwater, the North Carolina-based security contractor that protects U.S. diplomats in Iraq and has been accused of using excessive force against Iraqi civilians.

Rep. Henry A. Waxman, (D-Beverly Hills), chairman of the House Oversight and Government Reform Committee, has said that Krongard interfered to shield the administration from embarrassment on politically sensitive issues.

Last month, Krongard recused himself from investigations regarding Blackwater after it was revealed in a dramatic appearance at a House committee hearing that Krongard’s brother was on a Blackwater advisory board. Krongard had denied that his brother, Alvin B. Krongard, a former No. 3 official at the CIA, was connected to Blackwater until he was confronted at the hearing with paperwork indicating that his brother served on the board.

Krongard had also withdrawn from an inquiry into the construction of the new U.S. Embassy complex in Baghdad. And he battled subordinates’ accusations of abusive treatment.

Gonzalo Gallegos, a spokesman for the State Department, said: “We thank him for his dedication to public service and wish him well in the future.”

Krongard grew up in a family of modest means in Baltimore and moved from one success to another in life. He was an All-American lacrosse goalie at Princeton University, also studied at Harvard Law School and Cambridge University in England, and distinguished himself as a lawyer.

But his two years as a federal agency watchdog have proved different.

His confrontations with Congress brought out unflattering information about his family relations, including that he once sued his daughter and son-in-law over a home loan.

Waxman welcomed the resignation.

“Mr. Krongard’s decision removes an enormous distraction from the inspector general’s office and will allow the office to focus on its important oversight responsibilities,” Waxman said in a statement. “The committee will certainly take this new development into account.”

Krongard’s departure is the second at the State Department linked to Blackwater. Richard J. Griffin, the assistant secretary of State for diplomatic security who made key decisions regarding the department’s oversight of Blackwater, resigned in October.

paul.richter@latimes.com