On 8 July 1998, Voet was stopped by French Customs agents as he tried to cross the French-Belgian border close to Neuville-en-Ferrain, near Lille in northern France. In his Festina team car, the agents found large quantities of syringes and controlled substances including narcotics, erythropoietin (EPO), growth hormones, testosterone and amphetamines. He was arrested and the Festina cycling team was suspended from the race. Further investigation led to the suspension, arrest and prosecution of numerous Festina and TVM team riders and staff. In 2000, Voet went on trial. He was convicted, given a 10-month suspended sentence and (the equivalent of) a US$4,200 fine.
Voet's book Prikken en slikken" (translated as "Breaking The Chain") was released in 1999. In it, he claims to have revealed all that he knew regarding doping practices in the cycling world. The book also includes photographs of the written doping records he used to keep track of the different performance-enhancing drugs and dosages he had given to each of the team's cyclists. Those records were used in court as evidence during the trials of the Festina affair. Voet says he worked with the Festina team doctor, Eric Rykaert, whose opinion was that drug-taking could not be eliminated from cycling and that it would be better therefore to see that doping happened with medical supervision. Rykaert died soon after the Festina trial and Voet left the sport to become a bus driver. He has been declared persona non grata by the Tour de France management and been asked to stay away from the race even as a private individual. He does maintain contact with cycling, however, and sometimes appears at seminars aimed at a greater understanding and greater restriction of drug-taking in cycling.
In 2002 Union Cycliste Internationale (then led by Hein Verbruggen) sued Voet over specific claims in his book. In 2004 the UCI won the case, and in 2006 won the appeal. Voet had made various claims about UCI and Verbruggen's behavior related to the Laurent Brochard Lidocaine case at the 1997 UCI Road World Championships.
- "'Festina Affair': A timeline". BBC. 24 October 2000. Retrieved 2 March 2010.
- Knapp, Gerard. "An extract from ... Breaking the Chain, Drugs and Cycling - The True Story by Willy Voet". Cyclingnews. Future publishing ltd. Retrieved 2 March 2010.
- Voet, Willy (1999). Massacre à la chaîne. Calmann-Lévy. ISBN 2-290-30062-4.
- News for March 10, 2002, cyclingnews.com, Edited by Jeff Jones, section "UCI wants damages from Voet". retr 2012 10 22
- UCI wins legal battle against Voet Anthony Tan, cyclingnews.com, May 20, 2006, Updated: April 20, 2009, retr 2012 10 22
- The Secret Race: Inside the Hidden World of the Tour de France. By Daniel Coyle, Tyler Hamilton, Random House Digital, Inc., Sep 5, 2012, page 94, footnote