CHARLESTON, W.Va. (AP) - Federal prosecutors said Tuesday they have closed a nearly four-year investigation of U.S. Rep. Alan Mollohan, news welcomed by the West Virginia Democrat as Republicans jockey for a chance to challenge him in November.
Prosecutors never said exactly why they were looking into the 14-term congressman. The investigation appeared to focus on his financial disclosures and his role securing funds for nonprofit groups he helped create.
Mollohan maintained he had done nothing wrong and said investigators never contacted him. He said Tuesday he had earlier amended his annual financial reports to correct 20 mistakes that he called ''unintentional and immaterial.''
The U.S. Justice Department told his lawyer it has closed the case and is not considering charges, Mollohan said in a statement.
Ben Friedman, a spokesman for the U.S. Attorney's office in Washington, D.C., confirmed the office has ended its probe, which Mollohan blamed on what he called right-wing attacks and a ''politically motivated assault'' on his character.
The investigation started after the National Legal and Policy Center filed a 500-page complaint in February 2006 alleging that Mollohan consistently undervalued his assets on congressional financial reports.
He stepped down as the ranking Democrat on the House ethics committee in April of that year, and his campaign has since paid nearly $300,000 a D.C. law firm.
Mollohan is also chairman of an appropriations subcommittee that oversees the budgets of several federal agencies, including the Justice Department. He stepped aside from working on its funding requests in early 2007.
The conservative policy center said it targeted Mollohan after his reported assets jumped from between $170,012 and $562,000 in 2000 to between $6.3 million and $24.9 million in 2004. Mollahan said the change reflected booming real estate investments.
The center previously declined to provide a copy of its complaint to The Associated Press. Its chairman, Ken Boehm, stood by the allegations against Mollohan in a statement Tuesday.
''Any statement by Mollohan that the Justice Department spent four years investigating him because of a hollow partisan attack is a slap at both,'' Boehm said.
Scrutiny later extended to five nonprofit organizations that Mollohan helped set up in his district. Together, they have received hundreds of millions in federal funding earmarked by the congressman.
Officers and staff from the nonprofits have contributed to Mollohan's election campaigns. They include the Canaan Valley Institute, a clean water organization; the Vandalia Heritage Foundation, which promotes historic preservation; and the Institute for Scientific Research, which works with NASA and the U.S. Defense Department. Those three reported receiving subpoenas from the FBI in April 2006.
''These nonprofits are all about building West Virginia's economy and making our state a better place to live,'' Mollohan said in his statement.
Another national organization, Citizens For Responsibility and Ethics in Washington, has cited the allegations when routinely ranking Mollohan among the ''most corrupt'' members of Congress.
CREW Executive Director Melanie Sloan said Tuesday's development should allow the House ethics committee to resume a review of Mollohan. A House document leaked in October revealed the Justice Department had asked the committee to suspend its probe until federal prosecutors wrapped up their case.
''It's a far cry from you didn't do anything wrong,'' Sloan said of the federal case being closed. ''Just because conduct may not rise to a criminal level does not mean that it didn't violate House ethics rules.''
The House committee did not immediately respond to a request for comment Tuesday.
Mollohan has represented West Virginia's 20 northernmost counties in the 1st District since 1983. He filed for re-election earlier this month. At least seven Republicans - including three either well-known or backed by national Republicans - seek to challenge him. With the filing deadline Saturday, he does not yet face a May primary opponent.
Political analysts have recently started rating the reliably Democratic seat as in-play. Mollohan started 2010 with less than $65,000 in his campaign fund. But the investigation ending with no charges will help the incumbent, said Robert Rupp, a political science professor at West Virginia Wesleyan College.
''It removes a real personal vulnerability,'' he said.
The probe was a major focus of the GOP's 2006 bid to unseat Mollohan. But he beat Republican state lawmaker Chris Wakim with 64 percent of the vote and then ran unopposed in 2008.
Rupp said that this year, such factors as the economy and dissatisfaction with President Barack Obama will be more important.
Associated Press Writer Tom Breen contributed to this report.