Mary McFate was the kind of volunteer the gun-control movement in Pennsylvania prized. By all accounts, she was dedicated and diligent, humble enough to stuff envelopes yet bold enough to lobby U.S. senators.

Now it seems that the CeaseFire PA board member may have been more versatile than anyone could have imagined. According to Mother Jones magazine, she was a spy for the National Rifle Association.

Mother Jones reported that McFate was in fact Mary Lou Sapone, who made headlines in the 1990 when it was revealed that she had been hired by a surgical-equipment company to infiltrate the animal-rights movement.

As McFate, the magazine reported, Sapone covertly infiltrated gun-control groups for more than a decade and received payment from private security firms and the NRA.

During that time, she inserted herself into some of the most important gun-control organizations in the country and was part of discussions on national strategy and policy.

She lived in Grove City, Pa. - between Pittsburgh and Erie - and apparently moved to Florida several years ago.

As evidence of Sapone's role, the magazine cited a 2003 deposition by Tim Ward, former president of the Maryland-based security firm Beckett Brown International. Ward testified that he hired Sapone to gather intelligence for the NRA, according to the article.

How did the magazine connect McFate to Sapone? It called McFate's home phone number and asked for Sapone. The woman who answered acknowledged that she was Sapone, the magazine said. Phone listings show both names at that number.

Attempts to reach McFate/Sapone at her home phone in Sarasota, Fla., or by e-mail were unsuccessful. The NRA did not return requests for comment.

Phil Goldsmith, president of CeaseFire PA, said he had also tried to reach McFate after publication of the Mother Jones article Wednesday, to no avail. He said he would ask the 17-member board to remove McFate in the next 10 days if he did not hear from her.

"If I wasn't 63 years old and seen a lot in my life, I would have been shocked," said Goldsmith, a veteran of city politics as managing director to Mayor John F. Street.

The Freedom States Alliance, a coalition of nine gun-control organizations from New England to Minnesota, decided not to wait to hear from McFate; the group threw her off its board yesterday by conference call.

"She was in the room for discussions about what legislative goals would be set, what the strategy would be to pursue those goals, and was, it appears, being paid to share that information with the gun lobby," said Freedom States Alliance board member Angus McQuilken. "It is shameful."

McQuilken and others were quick to criticize, and to mock, the NRA.

"It's surprising that the NRA had nothing better to do but put a mole into an organization such as CeaseFire PA," said City Councilwoman Donna Reed Miller, who is locked in a legal battle with the state over gun-control legislation she cosponsored with Councilman Darrell Clarke. "It must mean they're afraid of something."

"It shows what radical ideologues have to do when they don't have the public or citizens on their side. They cheat," said Joe Grace, executive director for CeaseFire PA.

But the overriding emotion yesterday seemed to be not outrage but befuddlement at how McFate, seemingly one of the more militant members of the movement, could have pulled it off - and why.

"She must be very good at what she does, because a whole bunch of very smart people were completely hoodwinked by this," said Diane Edbril, CeaseFire PA's executive director between 2004 and 2007.

Edbril hosted McFate at her Radnor home in July 2007, when McFate flew up from her home in Sarasota to attend a CeaseFire PA board meeting.

"She was in my guest room. Was she looking through stuff in my house?" Edbril was asking herself yesterday.

Ona Hamilton, whose local Million Mom March group evolved into CeaseFire PA in 2002, asked McFate to be on CeaseFire PA's first board. McFate at the time was a board member for Pennsylvanians Against Handgun Violence. Hamilton said McFate would rail against her fellow board members in that organization for being too soft on the NRA, Hamilton said.

McFate did so much grunt work and provided so many helpful ideas that both Hamilton and Edbril suggested that, spy or not, she may have been a positive influence.

"I actually think she helped the movement rather than hurt the movement through all her volunteer efforts," Hamilton said. "I just don't see what she could have gained in terms of damaging information."

Hamilton last spoke to her friend in 2005, when McFate was trying to get elected to the national board of the Brady Campaign to Prevent Gun Violence. Hamilton voted for her; McFate still lost.

Bryan Miller, executive director of Ceasefire NJ, first met McFate in 1998, when she was in Philadelphia protesting an NRA meeting.

"We thought she was sort of a flake and not so bright, but hardworking and ready to show up for anything," Miller said.

"But she was always there, when I think about it," Hamilton said.

"She was always there."