The chairman of the House Judiciary Committee and 18 other House Democrats on Tuesday asked the attorney general to replace a government prosecutor with an outside lawyer to investigate the CIA's destruction of interrogation videotapes.

The request comes a day before the CIA's top lawyer, John Rizzo, is due to testify to the House Intelligence Committee about the tapes, which the CIA destroyed in November 2005. Recorded in 2002, they showed the harsh interrogation of two Al Qaeda suspects.

Attorney General Michael Mukasey on Jan. 2 appointed a Connecticut federal prosecutor to oversee the criminal investigation. Judiciary Committee Chairman John Conyers, D-Mich., said in a Tuesday letter to Mukasey that the Justice Department's ability to conduct an independent investigation is compromised because the CIA apparently consulted Justice and White House lawyers about the tapes and their destruction.

"The department has no business conducting the investigation and should instead turn to a special counsel," Conyers wrote. "Nothing less than a special counsel with a full investigative mandate will meet the tests of independence, transparency and completeness."

Without a special counsel there will be no final public report on the investigation, Conyers argued. He said he's also concerned that the investigation will not look at what other materials the CIA may have destroyed, or whether interrogators broke laws against torture.

The order to destroy the tapes was given by Jose Rodriguez, then the CIA's chief spy as head of the National Clandestine Service. Rodriguez had been scheduled to testify before the House committee on Wednesday, but his appearance was delayed because his attorney insists that Rodriguez be granted immunity from prosecution.