The Justice Department has launched a formal criminal investigation into the destruction of videotapes documenting the interrogation of two prisoners held at secret jails. On Wednesday, Attorney General Michael Mukasey appointed veteran federal prosecutor John Durham to oversee the probe. The move immediately came under criticism from Democrats who want an independent investigation from a special counsel. In a statement, House Judiciary Chair John Conyers said the probe should expand its scope to include other destroyed evidence and the nature of the interrogations that the videotapes captured.