Ropel testified Tuesday that Niazi told the informant that it was his "duty to engage in violent jihad."
Over a year, Monteilh further related in an interview, the FBI paid him sums ranging from $2,500 a month to as high as $11,200. Monteilh said he was cut loose as an informant in fall 2007 because members of the mosque he infiltrated began to suspect that he was working with the FBI.
Kenneth Piernick, a former FBI counter-terrorism official who is a private security consultant in Virginia, said parsing out what's true and what's not, even from someone deemed to be a reliable informant, can be challenging.
"You don't go talk to choirboys to get information on thugs," said Piernick, who retired from the bureau in 2003.
He said informants can be egotistical, manipulative and dishonest. Those who are getting paid, he said, have been known to "exaggerate information, or even invent it" to keep the money flowing.
Piernick said common reasons for discontinuing an informant include low-quality or unreliable information.
"In other words, he's not worth the effort," Piernick said.
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teresa.watanabe@latimes.com
scott.glover@latimes.com
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Times staff writer Christine Hanley contributed to this report.
