Searches aren't the only gray area for professional informants.
Dennis Mahon was a big-talking white supremacist who moved in some of the same circles as Thomas and even Oklahoma City bomber Timothy McVeigh. During the 1990s, Mahon's girlfriend -- a blond bombshell sporting a swastika tattoo -- was recruited to inform on him to the Bureau of Alcohol, Tobacco and Firearms (ATF). Her reporting never led to his arrest, but investigators retained one crucial piece of information: Mahon had a fatal weakness for women, especially if he thought he had a shot at sex.
In late 2004, the ATF decided it needed another informant next to Mahon, but this time she would be made, not found.
According to the Arizona Republic, ATF agent Tristan Moreland recruited Rebecca Williams, a former stripper with no criminal record and no previous connection to Mahon or white supremacy. Moreland preferred to "cast" his informants like a Hollywood director, rather than work with what he found, the newspaper reported.
By all accounts, Williams's motives for taking part in the investigation were pure. Her father and an uncle had been in law enforcement. "I kind of wanted to be a cop," she told the Republic.
Williams became, for all intents and purposes, a paid employee of the ATF. But because she was classified as an informant, she was not subject to the same scrutiny and regulation that would tie the hands of a trained undercover agent.
Much of her work was standard fare, flirting and talking with Mahon and getting him to open up (often on tape) about the 2004 mail-bombing of an Arizona diversity official, a case that Moreland was investigating. Mahon was ultimately convicted, based in significant part on Williams's testimony and recordings.
On one such video recording, Mahon lay naked in bed while talking with Williams, who ultimately put a towel over the camera to obscure what happened next.
Williams denied having sex with Mahon. Prosecutors claimed that "there was no use of sex to obtain evidence," which was not quite the same thing as saying, "There was no sex." Mahon's attorney asserted in closing arguments that Williams had slept with Mahon, though in an email interview she stipulated that "at the risk of sounding like President Clinton, it depends on how one defines 'sex.'"
Another counterterrorism case where the question of sex entered the scene involves Craig Monteilh, a paid FBI informant who says he was tasked to search for possible terrorist sympathizers among mosques in Orange County, California, where he pretended to convert to Islam to gain access.
Monteilh said he approached the job with considerable enthusiasm, taping hours of religious and cultural events before going public with a series of alarming, and often contradictory, stories about his misadventures, which are the centerpiece of an ongoing lawsuit against the FBI by southern California Muslim organizations.