(Photo by Stina Sieg - KJZZ)

The Phoenix VA hospital has been at the heart of the scandal over mismanagement of health care for veterans.

Independent federal investigators are looking into whether supervisors at the Department of Veterns Affairs retaliated against employees who filed dozens of whistle-blower complaints.

Carolyn Lerner, head of the United States Office of Special Counsel, said the complaints were filed in 28 states at 45 facilities, according to prepared testimony she planned to deliver before the House Veterans Affairs committee Tuesday night that was obtained by the Associated Press.

More than a third of the complaints have been filed since the scandal over inadequate VA healthcare and fraudulent records became public. Thirty complaints of retaliation have made it through an initial review stage and are being investigated further.

Lerner said her office has managed to block disciplinary action and a suspension against several VA employees who reported wrongdoing.

The VA announced Tuesday it would shake up its Office of the Medical Inspector after it was sharply criticized in a report from Lerner’s office last month.