Hillary Rodham Clinton's personal lawyer has told a Senate committee that emails and all other data stored on her computer server were erased before the device was turned over to federal authorities.

In a letter sent last week to Sen. Ron Johnson, the chairman of the Senate Homeland Security Committee, David Kendall said the server was transferred to the FBI on August 12 by Platte River Networks, a Denver firm hired by Clinton to oversee the device. Federal investigators requested custody of the server to learn whether the data stored on it was secure. The Senate committee made Kendall's letter public on Tuesday.

In exchanges with reporters earlier this week, Clinton said she was not aware if the data on her server was erased. Forensics experts told The Associated Press this week that many emails and other data can still be extracted from servers even after they are expunged.

Kendall, Clinton's long-time personal lawyer, also said that both he and another lawyer had been given security clearances by the State Department to handle a thumb drive containing about 3,000 emails that Clinton later turned over to the agency. Kendall said the thumb drive, which has also been since given to authorities, was stored in a safe provided in July by the State Department. Kendall did not say when he was given his clearance from State. The GOP-dominated Senate Judiciary Committee has separately asked Kendall if he had any access to Clinton's emails before he was given his security clearance.

Republican senators on both committees are pressing to see whether any emails sent or received by Clinton on the private server while she was secretary of state contained any sensitive or secret information that should have been only exchanged on secured, encrypted government communications portals. An inspector general for the State Department said recently that several emails sent to Clinton did include such classified material -- signaling that the transmission of those emails risked violating government guidelines for the handling of classified material.

Clinton campaign officials on Tuesday sought to show that the information contained in those emails did not risk spillage of classified data at the time they were sent to the former secretary of state.