Rep. Lamar Smith (R-Texas), chairman of the Judiciary Committee, is requesting interviews with seven administration officials as part of a probe into recent national security leaks.

In a letter to President Barack Obama, Smith asked to interview National Security Adviser Thomas Donilon, former White House Chief of Staff William Daley, Assistant to the President John Brennan, National Intelligence Director James Clapper and three other officials about recent highly publicized disclosures of material involving previously secret cyber-attacks on Iran, a terrorist “kill list” and extensive drone operations.

The move came after Republicans have questioned whether the administration’s own investigation into the matter is independent and called for a special prosecutor to be appointed.

Attorney General Eric Holder tapped District of Columbia U.S. Attorney Ronald C. Machen Jr. and Maryland U.S. Attorney Rod J. Rosenstein on June 8 to lead the criminal investigation into the leaks.

“The recent disclosure of national secrets is of great concern to all Americans. When national security secrets leak and become public knowledge, our people and our national interests are jeopardized. And when our enemies know our secrets, American lives are threatened,” Smith said in a statement.