A private Catholic school in France is to test the DNA of all male pupils and staff in an attempt to identify the rapist of a 16-year old girl who was assaulted in the school toilets. In the first time this mass screening has been carried out in a French school, 527 pupils and staff will be genetically tested starting today at the Fenelon Notre-Dame school in La Rochelle. The victim said she was unable to identify the rapist, who attacked her from behind in darkness after the light on an automatic timer switch went off, according to the prosecutor, Isabelle Pagenelle. But traces of DNA were found on her clothing. We have followed every lead before going down this route. We don't have any other choice Head teacher Chantal Devaux Those to be tested include 475 pupils, 31 staff and 21 other employees who were in the school in western France at the time of the attack on September 30 last year. The DNA is to be collected in saliva swabs over three days by 18 police officers at the school. But the genetic testing of teenagers has proved controversial, particularly as the authorities say that anyone who refuses to take part will be considered a suspect. Pierre Tartakowsky, president of the French League of Human Rights, told Le Parisien newspaper that the testing was "disproportionate, threatening and traumatising". Pagenelle said there was a significant probability that the attacker was from the school. Police had a list of all those on the premises at the time of the rape, she said. The school, in the centre of La Rochelle, has 1,300 pupils. "We have followed every lead before going down this route. We don't have any other choice," said head teacher Chantal Devaux, who informed pupils and their parents about the testing. The genetic-testing results will be known within a month.