A new book claims that musician Sheryl Crow witnessed former boyfriend Lance Armstrong engage in doping, then informed federal officials about his indiscretions.

In “Wheelmen,” a book about Armstrong’s downfall, Wall Street Journal reporters Reed Albergotti and Vanessa O’Connell explore several of the events that ultimately led to the cycling star’s public disgrace. But the most sensational aspect of the book concerns Armstrong’s relationship with Crow. According to Albergotti and O’Connell, Crow traveled with Armstrong to Belgium in 2004 and witnessed her then-boyfriend undergo an illegal blood transfusion, the New York Daily News notes.

According to an excerpt from “Wheelmen,” Armstrong openly discussed his blood doping regimen with Crow, whom he dated from 2003 to 2006. “Rather than try to hide the transfusion from [Crow], Armstrong was completely open about it,” the book excerpt reads. “He trusted that Crow would have no desire to tell the press or anyone else about the team’s doping program. He explained that it was simply part of the sport — that all cyclists were doing the same thing.”

The book also touches on Crow’s testimony during the federal investigation into Armstrong’s misdeeds. According to Albergotti and O’Connell, Crow spoke with federal investigators in 2011 in regard to a criminal probe into Armstrong’s blood doping.

“Wheelmen” claims that Food and Drug Administration investigator Jeff Novitsky offered Crow a proffer agreement in exchange for her testimony. If Crow agreed to cooperate honestly with prosecutors, she would be granted immunity from any criminal charges of her own.

Despite Crow’s apparent testimony, the federal investigation into Armstrong’s ties to blood doping failed to levy a penalty against the 42-year-old. The federal charges against him were dropped, without explanation, in 2012, the New York Daily News notes. However, the Justice Department is current pursuing additional legal action against Armstrong, claming that the cyclist and his teams accepted millions of dollars from the U.S. Postal Service, a former sponsor, under false pretenses.

The New York Daily News contacted Crow’s representatives on the accusations levied by “Wheelmen,” but she has yet to comment. “Wheelmen: Lance Armstrong, the Tour de France and the Greatest Sports Conspiracy Ever,” will hit bookstands on Tuesday.