Revealed! Singer Sheryl Crow saw ex-boyfriend Armstrong dope

Grammy Award-winning musician Sheryl Crow watched disgraced cyclist and former boyfriend Lance Armstrong get an illicit blood transfusion and later told federal investigators about what she had seen, according to a new book.

The New York Daily News, citing a book by Wall Street Journal reporters Reed Albergotti and Vanessa O'Connell, said Crow, who was dating Armstrong at the time of the transfusion in 2004, cooperated with investigators after being given immunity from prosecution.

"He trusted that Crow would have no desire to tell the press or anyone else about the team's doping program," the two authors wrote in Wheelmen: Lance Armstrong: the Tour de France and the Greatest Sports Conspiracy Ever.

"He explained that it was simply part of the sport -- that all cyclists were doing the same thing."

Armstrong has been stripped of his seven Tour de France titles and was banned for life from cycling last year after accusations he had cheated for years. In January, he admitted to using performance-enhancing drugs his career in an interview with television host Oprah Winfrey.

Image: Sheryl Crow and Lance Armstrong

Photograph: Kevin Winter/Getty Images for GQ