The groups she allegedly infiltrated were left reeling, wondering how they were duped for so long by someone with whom they closely worked.
"This reinforces what we have long known, that the gun lobby will go to any lengths, no matter how unethical, to protect the profits of the gun industry in this country, even at the expense of the over 30,000 Americans who lose their lives to gun violence each year," said McQuilken, whose organization kicked "McFate" off their board soon after learning her true identity.
"This person was a very good imposter. She knew all the right things to say," he said.
It makes sense she'd be a good imposter, though. According to the Associated Press, a 1997 resume for Mary Lou Sapone that surfaced during a Maryland business dispute listed her as an "intelligence and investigations" consultant and a former senior investigator specializing in "covert operations" for a Connecticut consulting firm.
The resume also listed Sapone as a president of a "Self-Improvement at Sea" program that provided lectures on world affairs, "life enrichment" and "intellectual history" on cruises. Meanwhile it listed her hobbies as hunting, trapping and fishing, shooting sports and "pugil stick fighting," the AP reported.
The gun-control groups are far from the first activist organizations to be infiltrated by corporations or other organizations, often larger and more powerful, than the activists.
In 2001, the British government launched an inquiry into a private intelligence firm with links to the U.K.'s MI6 spy service for infiltrating environmental activist groups to gather information to sell to oil companies, including Royal Dutch/Shell Group and BP, the Times of London reported.
In 2006, People for the Ethical Treatment of Animals sued the owners of Ringling Bros. circus and accused them of infiltrating animal rights groups, stealing documents and tapping phones.
But as they have been spied on, so too have activists spied.
One year before PETA accused the circus of allegedly spying, a New Jersey biomedical company accused the animal rights group of infiltrating and secretly videotaping its operations.
"This type of malicious activity by PETA, in which it conspires with individuals to lie about their intentions, to videotape and potentially disrupt medical research, and then to launch vile disinformation campaigns against pharmaceutical research companies, has got to stop," James Lovett, the lawyer for Covance, a biomedical industry leader with some of the world's largest animal-testing labs, told the AP at the time.
The infiltration of activist groups is neither new nor difficult, said Craig Dotlow, a former FBI special agent and spokesman for the Society of Former Special Agents of the FBI.
"The FBI used to do this kind of work a lot in the '60s, infiltrating groups like the Weathermen or the Black Panthers. All you really need to find is a good actor," he said. "It is a very unsophisticated but very successful technique. Find someone who can fit into the culture, who can be taught about the group and then make sure they cultivate friendships and work hard. Most of these groups have small budgets, and when they find someone who is dedicated and willing to work for free, they can move up the ranks pretty quickly."
Dotlow added, "It is mostly about education. You need your candidate to know enough about the group so he can talk intelligently about their issues. Then you create a record of involvement, get your name in paper, write an editorial so it appears you have been committed for a long time."
Companies that spy on other companies or each other, Dotlow said, are committing a crime and for that reason many won't do it.