WASHINGTON - Federal agents raided the office and home of U.S. special counsel Scott Bloch on Tuesday while investigating whether the nation's top protector of whistle-blowers destroyed evidence potentially showing he retaliated against his staff.

Computers and documents were seized during the raids by at least 20 agents of the FBI and the White House Office of Personnel Management.

The raids mark the latest twist in what critics describe as Bloch's bizarre tenure as the head of the agency responsible for protecting the rights of federal workers and ensuring that federal whistle-blowers are not subjected to reprisals.

He has been on the hot seat since he took office in 2004, in part for closing hundreds of whistle-blower cases allegedly without investigating them.

A group of current and former Office of Special Counsel workers filed a complaint against Bloch in 2005, accusing him of retaliating through intimidation and involuntary transfers against those who opposed his policies. The employees also accused Bloch of refusing to protect federal workers from discrimination based on sexual orientation. Those charges are being investigated by the inspector general at the Office of Personnel Management.

A year later, in December 2006, Bloch paid $1,000 in taxpayer money to have an outside tech company, Geeks on Call, scrub his government computer. In March, a congressional aide said, Bloch told House Oversight and Government Reform Committee investigators that the data wipe was done to protect government and personal information, not to destroy it.

Tuesday's raids were done in connection with a criminal investigation of whether Bloch obstructed justice and potentially lied to Congress, according to law enforcement officials.

Bloch has denied any wrongdoing.