Mary Fallot looks as unlike a terrorist suspect as one could possibly imagine: a petite and demure white Frenchwoman chatting with friends on a cell-phone, indistinguishable from any other young woman in the café where she sits sipping coffee.
And that is exactly why European antiterrorist authorities have their eyes on thousands like her across the continent.
Ms. Fallot is a recent convert to Islam. In the eyes of the police, that makes her potentially dangerous.
The death of Muriel Degauque, a Belgian convert who blew herself up in a suicide attack on US troops in Iraq last month, has drawn fresh attention to the rising number of Islamic converts in Europe, most of them women.
"The phenomenon is booming, and it worries us," the head of the French domestic intelligence agency, Pascal Mailhos, told the Paris-based newspaper Le Monde in a recent interview. "But we must absolutely avoid lumping everyone together."
The difficulty, security experts explain, is that while the police may be alert to possible threats from young men of Middle Eastern origin, they are more relaxed about white European women. Terrorists can use converts who "have added operational benefits in very tight security situations" where they might not attract attention, says Magnus Ranstorp, a terrorism expert at the Swedish National Defense College in Stockholm.
Ms. Fallot, who converted to Islam three years ago after asking herself spiritual questions to which she found no answers in her childhood Catholicism, says she finds the suspicion her new religion attracts "wounding." "For me," she adds, "Islam is a message of love, of tolerance and peace."
It is a message that appeals to more and more Europeans as curiosity about Islam has grown since 9/11, say both Muslim and non-Muslim researchers. Although there are no precise figures, observers who monitor Europe's Muslim population estimate that several thousand men and women convert each year.