Updated: 5:27 p.m.

Chuck Brimmer has resigned as chief of staff to Rep. Peter Visclosky (D-Ind.) after being served with a subpoena as part of the federal grand jury probe of the PMA Group, a now-defunct lobbying firm.

The news came as Visclosky announced Tuesday that he is handing off control of the energy and water spending bill while the federal inquiry proceeds.

Visclosky spokesman Jacob Ritvo confirmed that Brimmer “has retired,— citing “respect for the process— in declining to comment further.

Visclosky on Friday announced that some staffers — and his Congressional and campaign offices — had been subpoenaed in the probe. Brimmer disclosed the development in a letter that was read into the Congressional record on Tuesday. He was the only Visclosky aide to report being served.

Brimmer has worked for Visclosky on and off since at least 2000, according to salary figures posted on LegiStorm, a Web site that tracks Congressional information. While on Visclosky’s payroll, Brimmer mostly split his time between the lawmaker’s personal office and the Appropriations Committee.

Brimmer left Visclosky’s staff in February 2003 to serve as chief of staff to then-Rep. Bob Matsui (D-Calif.). He was replaced by Rich Kaelin, who had served as Visclosky’s legislative director. But Brimmer returned to Visclosky’s staff in October of that year, and Kaelin left for a lobbying gig with PMA.

While it is not clear whether Brimmer left voluntarily, the move appears in line with an aggressive approach Visclosky has taken toward confronting the scandal. Most recently, his decision to relinquish control of the energy and water bill came without pressure from more senior Democrats, according to a Democratic aide.

“I have represented the people of Northwest Indiana to the best of my ability and I have always abided by the law and adhered to the rules and code of ethics of the House,— Visclosky said in a statement announcing the decision. “As we work through this process, I intend to work as hard as I always have on behalf of the people of Northwest Indiana.—

Visclosky, who chairs the House Appropriations Subcommittee on Energy and Water Development, said he will ask Rep. Ed Pastor (Ariz.), the second-ranking Democrat on his panel, to handle the measure.

It was the latest in a series of moves the Indiana Democrat has made to distance himself from PMA. Visclosky did not request earmarks for any former PMA clients in this year’s defense spending bill, he pledged to return $18,000 in contributions from suspected straw-man contributors linked to the firm and he has broken party ranks to support a call for the ethics committee to investigate PMA’s ties to senior appropriators.

The strategy marks a sharp break from Visclosky’s record of support for the firm: He helped its clients secure about $34 million in earmarks over the last two years, according to Taxpayers for Common Sense. And PMA and its clients have been a top source of funds for Visclosky, contributing about $1.4 million in campaign contributions since 1998, according to the Center for Responsive Politics.