The CBS (searchproducer being investigated for arranging a meeting between a controversial source and John Kerry's presidential campaign (searchpreviously faced scrutiny for agreeing to act as a go-between between two federal prisoners in 2001, FOX News has learned.

Mary Mapes (searchis already in hot water over her role in accepting manufactured documents about President Bush's Texas Air National Guard service (searchand then arranging a phone meeting between Kerry campaign adviser Joe Lockhart (searchand the source of the documents, retired Guardsman Bill Burkett (search).

In 2001, the warden of a high-security federal prison in Florence, Colo., wrote Mapes telling her that her actions trying to facilitate mail between the two prisoners violated federal regulations. In the letter, Warden J.E. Gunja spells out a scheme in which Mapes agrees to help secretly pass information between convicted white supremacist Peter Langan and another federal prisoner.

"Phone monitoring reveals that you agreed to this request ... This investigation was based, in part, on inmate Langan's admission to this attempt," Gunja wrote.

"Your attempted misuse of the special mail privileges placed members of the public at risk," the letter reads.

Click to read the letter: Page 1 | Page 2 (pdf files).

In the letter, Gunja then revoked Mapes' correspondence, telephone and interview privileges with the high security inmate. He also copied Mapes' boss, Jeff Fager (search), the executive producer of "60 Minutes," who is on record singing the praises of Mapes.

"Mary Mapes has always been a first-class producer with an impressive body of work," Fager told the New York Times in its Wednesday edition.

CBS News confirmed late Wednesday that Mapes is still employed by the network, but declined to comment on the letter to Mapes from the warden.

The correspondence was uncovered just as CBS appointed a blue-ribbon commission to investigate the CBS memo scandal that has unfolded in the last two weeks. The commission is comprised of retired CEO of the Associated Press Louis Boccardi and former Republican U.S. Attorney General Dick Thornburgh.

The scandal began shortly after CBS reported during "60 Minutes II" that Bush was AWOL from his Guard duty. Almost immediately, the authenticity of the memos cited in the report, allegedly written by Bush Guard supervisor Lt. Col. Jerry Killian (search), was called into question. Most document experts now say the memos are forgeries.

Kerry campaign officials confirmed again on Wednesday that Mapes, who produced the report, also arranged a phone call between Burkett and Lockhart. But that's not enough for Republicans, who now have raised questions suggesting the Kerry campaign may have known more than it's indicating.

"The fact of the matter is that we now have information that there was coordination and communications between CBS, the Kerry campaign and this source, who has now been discredited. The question remains — what was the quid pro quo?" asked Bush communications Director Dan Bartlett.

Click on the video box at the top of this story to watch a report by FOX News' Brian Wilson.

FOX News' Brian Wilson contributed to this report.