Jacques De Ceaurriz:Anti-doping scientist who led the Tour de France's drugs-testing programme for 12 years

Almost every summer on the Tour de France's final approach to Paris, the peloton sweeps through the suburb of Châtenay-Malabry, and Jacques de Ceaurriz would always take a few minutes off work to see the riders go by.

Afterwards, he would go back to directing France's biggest anti-doping laboratory, situated in a boulevard a block away from the race, and continue his decade-long pursuit of cheating athletes – some of whom he had just seen ride past him a few minutes before.

Upon his death, the tributes flooded in for de Ceaurriz, with the World Anti-Doping Agency director John Fahey saying, "The fight against banned drugs in sport has lost one of its most eminent scientists."

But de Ceaurriz was not just one of the world's leading anti-doping analysts, directly or indirectly involved in judging the results from hundreds of cases during the 12 years he headed the Châtenay-Malabry lab. A former pharmacist and Paris university professor, in 2000 de Ceaurriz also co-researched and developed the urine test for the banned blood booster EPO, the drug of choice among athletes in endurance sports for the previous decade. The test was considered such a spectacularly important advance in the anti-doping war that it was immediately put to use in the 2000 Olympic Games – and a few years later it was back in the media spotlight again.

In 2005, both the tests and de Ceaurriz came under severe scrutiny when the French sports newspaper L'Équipe published allegations that urine samples given by Lance Armstrong in the 1999 Tour had shown traces of EPO. A huge scandal ensued, with Armstrong – who had retired a few days before with seven Tour de France wins to his name – furiously denying the claims, but de Ceaurriz insisted the tests were reliable. However, he refused to confirm that the allegedly positive samples were Armstrong's and said that the retroactive testing had been carried out purely for research purposes.

Less than a year later, de Ceaurriz had another massive run-in with another American Tour winner, Floyd Landis. Landis had taken the Tour with a blistering lone attack in the Alps, but even as he stood on the Champs-Élysées soaking up the applause, rumours were beginning to spread that he had returned an initial positive test for an artificial version of testosterone.

Landis challenged the results as aggressively as Armstrong, alleging everything from consuming too much Jack Daniels whiskey the night before to poor laboratory procedure. However, after a year-long investigation, the result from the Châtenay-Malabry lab was upheld and Landis became the first rider to be stripped of his Tour de France title for doping.

For a more ambitious person than de Ceaurriz, the Landis affair could have kick-started a career in sport's corridors of power. But rather than exploit it to his advantage, de Ceaurriz – who was often said to feel empathy for the riders whose samples he analysed – simply went back to work.

"These practices have always existed in sport and they will always exist... I have no moral judgement to make," he once told L'Équipe.

"When I get to know the athletes during the analysis of the second samples [the so-called "B" tests which confirm or annul a positive case in doping] and when I sense their anxiety and distress, I don't feel proud. I really don't feel proud at all."

Alasdair Fotheringham

Jacques de Ceaurriz, anti-doping scientist: born 1950; married Elizabeth (one son, one daughter); died Paris 5 January 2010.