Congressmen Lamar Smith and Frank Wolf want investigations by the FBI and the Department of Justice Inspector General into charges of improper political interference with prosecution of foreign nationals who allegedly stole U.S. space defense secrets and passed them to China.

"We have been told by sources close to this investigation that the FBI's case is substantially complete and was referred to the U.S. Attorney for the Northern District of California for prosecution, but it has been stalled for more than a year and that an assistant U.S. attorney was reassigned from the case," Smith and Wolf said in Feb. 8, 2013, letters to FBI Director Robert S. Mueller and DOJ IG Michael Horowitz.

"We are deeply concerned that political pressure may be a factor," the two congressmen said.

Smith, a Texas Republican, is chairman of the House Committee on Science, Space and Technology Committee, while Wolf, a Virginia Republican, heads the panel's appropriations subcommittee with oversight of the National Aerospace and Space Administration.

The FBI's targets were foreign nationals working at NASA's Ames Research Center near San Francisco. The center's director is retired Air Force Gen. Simon "Pete" Worden.

"It is our understanding that this illegal technology transfer may have involved classified Defense Department weapons system technology to foreign countries, including China, potentially with the tacit or direct approval of the center's leadership," Smith and Wolf said in their letters.

Smith and Wolf also said they were told "that key evidence from the hard drive of one suspect's computer was corrupted, as were all the back-up copies in the government's possession."

The two men requested a review of the case from the time it was referred by the FBI to the Justice Department, including "the series of questionable delays and reassignment of the assistant U.S. attorneys managing this case."

The case has also drawn attention in the Senate where Sen. Charles Grassley of Iowa, the ranking Republican on the Senate Judiciary Committee, raised the issue with NASA Administrator Charles Bolden in an April 18, 2012, letter.

In his letter to Bolden, Grassley said he was concerned that "it is alleged that in recent years, Director Worden allowed foreign nationals to access" the Ames facility.

"These foreign nationals have allegedly obtained NASA secrets and cutting- edge technology, while not possessing the proper clearance in violation of International Traffic in Arms Regulations (ITAR)," Grassley said.

The ITAR bars non-U.S. citizens from access to the sensitive technology required for space-based defensive weaponry. Among the Ame's facility's major task is research and development of space defense technology, including classified propulsion rockets designed to defend against incoming intercontinental ballistic missiles.

To date, Grassley has not received a response from Bolden.

Melinda Haag, U.S. Attorney for the Northern District of California, told The Washington Examiner that her office did not seek authority from Washington to bring charges against foreign nationals. But she declined to say whether the case remained open.

Richard Pollock is a member of The Washington Examiner's Watchdog reporting team. He can be reached at