Others at the network noted that the producer on the Texas Air National Guard segment was the highly regarded Mary Mapes, who helped "60 Minutes" break the Abu Ghraib prison scandal in Iraq.
"It's hard to separate legitimate concern from political blowback and propaganda," Heyward said.
On last night's "CBS Evening News," Rather defended the piece against what he called the "counterattack." He interviewed Matley, who said he concluded after comparing Killian's signature on the memos to other undisputed documents that "yes, it's the same person."
Rather noted the critics' claim that typewriters in the Vietnam War era could not produce a raised superscript, such as the letters "th," but he maintained: "Some models did." As for contentions that the memos were written in a more modern font called Times New Roman, Rather said: "The company that distributes this typeface says it has been available since 1931."
Other experts have told The Washington Post that the spacing between letters is suspicious for documents of that era. But Rather cautioned that the memos become less clear as they are downloaded and photocopied.
In the interview, Rather said the controversy should not detract from these questions raised by the program: "Did a wealthy oilman who was a friend of the Bush family come to the speaker of the Texas House and ask for preferential treatment for George Bush, and did he get it? Did or did not then-Lieutenant Bush refuse to obey a direct order from a military superior?"
In 1999, "60 Minutes" apologized, as part of a legal settlement with a Customs Service official, for reporting on a memo that was later found to be fake.
Matley, who told Rather last night that he knew the Bush documents would be professional "dynamite," has been involved in high-profile cases, including a 1997 controversy over purported John F. Kennedy documents. After "60 Minutes" cast doubt on those documents, the man who unearthed them, Lawrence Cusack III, retained Matley in a suit against CBS that was rejected in court. Matley could not vouch for the documents' authenticity.
Staff writer Mike Allen contributed to this report.