Lance Armstrong crosses the finish line of the Half Full Triathalon on Oct. 7 in Ellicott City, Md. (Steve Ruark/Associated Press)

Girding for the expected release later this week of documents detailing Lance Armstrong’s alleged use of performance-enhancing substances, a lawyer for the retired cyclist sent a sharply worded five-page letter to the U.S. Anti-Doping Agency on Tuesday castigating the motives and methods of what he called a “taxpayer-funded witch hunt” against his client.

The letter, written by Timothy J. Herman of Austin, accuses USADA of waging a vendetta against Armstrong and basing its case on testimony that has been pressured and coerced from witnesses, including two, former Armstrong teammates Floyd Landis and Tyler Hamilton, it characterized as “serial perjurers.”

USADA in June accused Armstrong, a seven-time Tour de France winner, of using banned substances and blood transfusions during his career and covering up the evidence. Armstrong’s efforts to battle the charges in a Texas court failed, with the judge ruling that the dispute was properly settled through arbitration.

In August, Armstrong stunned the cycling community and sporting world by announcing he was opting out of arbitration and dropping his fight against the agency after defending himself against similar allegations for years. In response, USADA banned Armstrong for life and stripped him of his record seven Tour de France titles, explaining that in refusing to defend himself the cyclist had forfeited any claim to the achievements.

All of this occurred against the backdrop of a global turf war, of sorts, between USADA and the sport’s international governing body, the International Cycling Union (UCI), over which agency held jurisdiction over the Armstrong matter. Once USADA leveled its charges against Armstrong, UCI asked the agency to present its case.

That is the long-awaited evidence that is expected to be forthcoming this week. It’s unclear, however, whether USADA’s report (dubbed “a reasoned decision”) to UCI will include the full file of evidence it has compiled, evidence Armstrong has yet to see or respond to, or a simple summary of how USADA reached its conclusions.

Asked to comment on Herman’s letter, USADA spokesperson Annie Skinner wrote via e-mail: “The rules require us to provide a reasoned decision in every case, and we are happy to let the evidence speak for itself.”

USADA is believed to have accounts from multiple former teammates of Armstrong testifying about his participating in banned blood-doping practices.

If UCI approves of USADA’s methods and finds its evidence persuasive, it’s expected to endorse the conclusions. If not, the matter is expected to be referred to the international Council for Arbitration in Sport.

Though Armstrong, 41, has retired from competitive cycling and is banned from sanctioned cycling events and triathlons, he continues to compete in unsanctioned triathlons, such as Sunday’s 70-mile Half Full in Elliott City, which he won in 4 hours 16 minutes.