Testing began Monday at Fenelon-Notre Dame high school in western France. All those who received summonses last week were warned that any refusal could land them in police custody, and no one rejected the sweeping request to test the high school's male population.
The testing of students, faculty and staff at the school is expected to last through Wednesday, with 40 DNA swabs recovered inside two large study halls. Prosecutor Isabelle Pagenelle said investigators had exhausted all other leads in the Sept. 30 rape of the girl in a dark bathroom at the school.
"The choice is simple for me," she said. "Either I file it away and wait for a match in what could be several years, or I go looking for the match myself."
While there have been other situations in which DNA samples have been taken en masse, the case is complicated for France, where acceptance is widespread for DNA testing and a national database maintains profiles of people detained for even minor crimes. But children's civil liberties are considered sacred, especially within schools.
France has stringent privacy protections — Google, for example, has come under legal attack for storing user data, as well as for lapses in images from Street View. Questions of criminality are a different matter — the government's DNA database has expanded radically since it was first created in 1998, and now encompasses 2 million profiles, or about 3 percent of the population.
"It's clearly a situation where people do not have a choice," said Catherine Bourgain, a genetic researcher and author of "DNA, Superstar or Supercop." ''One you have a DNA file it's very difficult to get that information erased."
Authorities have promised to discard the DNA collected once a donor is eliminated as a suspect, but Bourgain said she hoped that would also include the profile information, which during the usual course of French investigations is computerized and transmitted to the database.
Police recovered genetic material from the girl's clothing but found no matches among current profiles.
"This happened during the school day in a confined space," Chantal Devaux, the private Roman Catholic school's director, told French media. "The decision to take such a large sample was made because it was the only way to advance the investigation."
Summonses went out last week to 475 teenage students, 31 teachers and 21 others — either staff or males who were on campus at the time. Pagenelle's office, which required parental permission for minors, promised to discard any DNA results from people who were eliminated as suspects.
"Even if they have the agreement of their parents they could refuse," Jean-Francois Fountain, La Rochelle's mayor, told RTL radio. "I'm trying to put a more positive view of things: If you do this, you clear yourself. There are hundreds of people today who will be cleared."
Devaux acknowledged that all the results could still come back negative, sending investigators back to the drawing board.
From a legal standpoint, the decision is completely logical, said Christopher Mesnooh, an American lawyer who works in Paris.
"Of the 500 or so men there's really only one who should have any concern," Mesnooh said. "What you have to do in this kind of case is you have to balance each person's right to privacy against what happened to this girl."
Such testing has occurred in the past. A small town in rural Australia, Wee Waa, tested the entire male population or about 500 men in 2000 after the rape of a 93-year-old woman. It led to the conviction a farm laborer, Stephen James Boney.
English police trying to solve the rape and murder of two teenage girls in the village of Narborough were the first to use mass DNA collection in 1986, sampling 5,000 men in the earliest days of genetic testing. Police found the killer, Colin Pitchfork, after he asked a friend for a substitute blood sample.
France has also used DNA dragnets, including in 1997 when police trying to solve the rape and murder of a 13-year-old British girl ordered testing for about 3,400 men and boys. In 2004, investigators trying to solve the murder of an 11-year-old boy took 2,300 samples. Neither crime was solved.
Last year, a judge in Brittany ordered DNA tests for all 800 men and boys ages 15 to 75 living in a town plagued with arson fires. The man ultimately charged, a local grocer, had been tested but was arrested only after two more fires and more investigation.
When the DNA database was created, French privacy rights advocates said they were comfortable with it because it had clear limitations, said Jean-Pierre Dubois of the French League of Human Rights. Over time, he said, those limits have blurred.
"We are very surprised that the police officers have not been able to be a bit more precise. When you make an inquiry, you have other evidence and other testimony," Dubois said. "Otherwise, you could say why only the people in the school? Why not all the inhabitants of the town or the region?"
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