An outgoing federal appointee to the board overseeing the $6 billion Dulles Rail project took a parting shot at the nation's top transportation official, accusing him of meddling in local politics and calling his office's investigation of the board a "political witch hunt."

Bob Brown this week told Transportation Secretary Ray LaHood that the federal investigation of the Metropolitan Washington Airports Authority was of "questionable lawfulness" and "far beyond the traditional role of U.S. DOT in local project development and execution."

Brown also said there was "no legal basis" for LaHood to appoint an accountability officer to monitor the airports authority and no right to launch an investigation of the authority that last May revealed that authority board members were spending lavishly on meals and travel and dolling out hundreds of thousands of dollars in no-bid contracts.

"Most members of the airports authority believed that the inspector general was acting far beyond the scope of his legal authority," Brown wrote, noting that one board member called the investigation a "political witch hunt."

Brown told The Washington Examiner that he wrote to LaHood because he believes the federal government is deflecting attention from the real issue: That tolls on the Dulles Toll Road used to finance the rail project will soar because the federal government wasn't contributing more.

"They don't want to talk about that. But that is indisputable. These tolls will be double digit tolls in a very few years," said Brown, a longtime chairman of the airports board's finance committee. "The people that have made the most noise about the authority's deficiencies, real and alleged, are the people who are doing the least for this project, and that's the governor of Virginia and the secretary of transportation. They both have the ability to keep these tolls from going through the roof, and neither of them has stepped up to do it."

One-way tolls on the Dulles Toll Road are expected to rise to $4.50 in 2015 and may go as high as $8.75 by 2023, authority estimates show.

A spokesman for LaHood said the department hasn't had a chance to review Brown's letter.