Traces of DNA on an orange juice bottle and a surveillance video of a man praying in a mall led to the arrest Wednesday of a young suspect accused of stabbing a French soldier who was patrolling a crowded area just outside Paris, officials said.

The attack came days after a British soldier was slain on a London street in broad daylight, raising fears of potential copycat strikes.

The French suspect, identified only by his first name Alexandre, was captured on camera Saturday offering a Muslim prayer in a corner of a busy shopping mall 10 minutes before he went after the soldier with a knife in the La Defense financial and shopping district, said the prosecutor, Francois Molins. The 22-year-old suspect was arrested outside Paris at the house of a friend who has not been implicated, Molins said.

The French soldier is recovering from his injuries and has been released from the hospital.

"The suspect implicitly confessed when he told police `I know why you're here,'" Molins said Wednesday at a news conference in Paris. "Given the attack in London, immediately Saturday we considered the possibility this was terrorism."

The suspect, who was unemployed and homeless, was identified through DNA he had left on a plastic juice bottle and already known to law enforcement for his ties to radical Islam, said Christophe Crepin, spokesman for the police union UNSA.

Molins said the man first came under scrutiny after a street prayer in 2007 and authorizes had his DNA profile.

Under French anti-terrorism law, he can be held for 96 hours without charge.

French security forces have been on heightened alert since the military intervened in the African nation of Mali in January to regain territory seized by Islamic radicals. Yet even before the French military action in Mali, French soldiers were considered possible targets at home by local radicals.

Last year, three French paratroopers were killed by a man police described as a French-born Islamic extremist. Mohamed Merah went on to attack a Jewish school in southern France, killing a rabbi and three Jewish children in March 2012 before being killed later that month in a gunbattle with police.

"I have said before there are dozens, if not hundreds of potential Merahs in our country," Interior Minister Manuel Valls told the iTele network.

___

Follow Lori Hinnant at https://twitter.com/lhinnant