By Jerry Markon
Washington Post Staff Writer
Sunday, December 5, 2010; 12:47 AM

IRVINE, CALIF. - Before the sun rose, the informant donned a white Islamic robe. A tiny camera was sewn into a button, and a microphone was buried in a device attached to his keys.

"This is Farouk al-Aziz, code name Oracle," he said into the keys as he sat in his parked car in this quiet community south of Los Angeles. "It's November 13th, 4:30 a.m. And we're hot."

The undercover FBI informant - a convicted forger named Craig Monteilh - then drove off for 5 a.m. prayers at the Islamic Center of Irvine, where he says he spied on dozens of worshipers in a quest for potential terrorists.

Since the 2001 terrorist attacks, the FBI has used informants successfully as one of many tactics to prevent another strike in the United States. Agency officials say they are careful not to violate civil liberties and do not target Muslims.

But the FBI's approach has come under fire from some Muslims, criticism that surfaced again late last month after agents arrested an Oregon man they said tried to detonate a bomb at a Christmas tree-lighting ceremony. FBI technicians had supplied the device.

In the Irvine case, Monteilh's mission as an informant backfired. Muslims were so alarmed by his talk of violent jihad that they obtained a restraining order against him.