WASHINGTON — It was at the Houston Livestock Show and Rodeo in February that retired National Guard Lt. Col. Bill Burkett came to have the documents that could affect a presidential election and Dan Rather's career.

From the rodeo, Burkett took the National Guard records that purported to shed negative light on President Bush's military career to a West Texas cold storage locker where, according to Burkett's lawyer, they remained until CBS sweet-talked them out of his client.

Now, says attorney David Van Os, Burkett — never shy about casting negative light on Bush — regrets getting involved. CBS News and Rather said Monday they can no longer vouch for the authenticity of the documents, citing Burkett's lie to them about who gave them to him.

Van Os acknowledges Burkett, a West Texas rancher, lied to protect his source. But that transgression pales, Van Os said, compared to how CBS has mistreated Burkett and mishandled the documents.

To this day, according to his lawyer, Burkett does not know if the documents are authentic and isn't really sure who gave them to him. They were turned over to CBS with two caveats, he says: Burkett would never be identified as their source and CBS would check out their authenticity.

CBS spokeswoman Kelli Edwards said the network would not respond to Van Os' claim about the caveats.

In an interview aired Monday night on CBS Evening News, Burkett said, "I also insisted when I sat down with your staff in the first face-to-face session before I gave up any documents I wanted to know what they were going to do with them. And I insisted that they be authenticated."

The saga, which continued Monday with CBS and Rather apologizing for airing the documents, had its roots on another network. Van Os, a Democratic candidate for the Texas Supreme Court, said the twisted tale had its roots on a cable TV political gabfest earlier this year.

Burkett got a call "out of the blue" from someone who had seen him on MSNBC's "Hardball with Chris Matthews" in February discussing his longstanding allegation that Bush aides ordered the destruction of the then-governor's National Guard records in Austin. There are some old National Guard records that Burkett needs to see, he was told.

The caller suggested a meeting in Houston. Van Os said Burkett, not awash in money, was not interested in making the trip. But, Burkett told the caller, maybe they could get together in March when Burkett would be at the Houston rodeo in his capacity as a trustee of the Texas Simmental Association, a group that promotes a cattle breed.