The threat of extremist violence has shaped Jennifer Arbittier Williams’ life more than most.

When she was 15, a great-uncle, Leon Klinghoffer, was killed by Palestinian hijackers aboard the Mediterranean cruise ship the Achille Lauro in 1985.

At 30, she watched in horror from the patio of the Manhattan law firm where she was working as a young associate as al-Qaeda plotters flew planes into the World Trade Center.

She moved back to Philadelphia shortly after for a job at the U.S. Attorney’s Office, where she became the go-to prosecutor for terrorism cases and eventually chief of its national security unit.

And so, when she was tapped earlier this year to lead the office as acting U.S. attorney for Philadelphia and the surrounding counties — two weeks after the deadly insurrectionist attack on the U.S. Capitol — it was only natural that she would choose a program aimed at defusing extremist threats as the signature focus of her tenure.

Last month, Williams — who succeeds U.S. Attorney William M. McSwain — launched the Threat Intervention and Prevention (TIP) Network, a collaboration among more than a dozen regional law enforcement offices and local businesses, nonprofits, schools, and community groups.

The aim: to prevent incidents of mass violence by sharing intelligence and serving as a resource to organizations seeking guidance on how to assess and mitigate risks from within and without. The network will draw on mental health experts, religious mentors, and community leaders trained in counseling people at risk of committing extremist violence. The hope is to reach them before they can act.

“The goal is not prosecution,” Williams said in a recent interview. “When somebody snaps, they don’t really snap in a moment. There are clues and problems. The goal is to train people in the community to spot those things [and] come up with creative ways to approach this individual and stop them from moving from their troubled life to an act of mass violence.”

And as concerns over political polarization, mass shootings, and domestic terrorism have reached new heights, demand for such a resource is high.

In just the month since the network was launched a 21-year-old Georgia man killed eight in a series of mass shootings concentrated in metro Atlanta’s Asian community, a man in Colorado opened fire at a supermarket resulting in 10 deaths, and federal prosecutors in Washington have charged dozens of Americans so animated by their sense of political grievance that they violently attacked the Capitol on Jan. 6.

Michael J. Driscoll, special agent in charge of the FBI’s Philadelphia Division, a lead participant in the TIP Network, said his agents have been fielding an increasing number of calls from businesses, community groups, and religious organizations unsure of how seriously to worry about disaffected employees, troubled students, or anonymous threats they have received.

“Recent events have fanned the flames of concern,” he said. “In the past several months, we’ve received more and more inquiries as to ‘How do I know whether an individual in my organization poses a threat?’”

After an 18-year career prosecuting terrorism cases, Williams, 50, is more equipped than most to answer such a question.

During that stint, she oversaw some of the U.S. Attorney’s Office’s highest-profile investigations, including the 2010 prosecution of Colleen LaRose, the Montgomery County woman who adopted the screen name “Jihad Jane” to spread jihadist screeds online and was charged in an assassination plot against a Swedish cartoonist.

But it was Williams’ dealings with one of LaRose’s codefendants that offered a glimpse of the type of pre-prosecution intervention she is envisioning with her TIP Network.

Mohammed Hassan Khalid — a 15-year-old son of Pakistani immigrants in Baltimore — met LaRose online and was quickly drawn into the world of Islamic extremism. Intelligent and quick with technology, he began translating recruitment materials into English for al-Qaeda and became embroiled with LaRose’s assassination plot.

As investigators zeroed in on his identity and learned he was a troubled but bright student with a hefty scholarship awaiting him at Johns Hopkins University, they hoped they could avert an arrest that might derail his promising future.

“We all agreed that the FBI should go to his house, talk with his parents, show him [LaRose’s] indictment and tell him you’re messing around with very dangerous people and need to step away,” Williams recalled.

Khalid didn’t heed their warning and after continued communication with his overseas extremist handlers, in 2011 he became the youngest person ever charged in the United States with terrorism offenses. But while that intervention was unsuccessful, Williams has high hopes that her new endeavor can avert similar situations.

She acknowledges it may take work to convince potential community partners that sharing concerns over individuals with law enforcement won’t ultimately lead to that person’s arrest. Similar community partnership programs aimed at preventing Islamic extremist attacks launched in several cities were met with skepticism from activists who feared they would be used — and in some cases were used — as a soft form of surveillance or for developing investigative informants.

“This is not a way to take traditional law enforcement tips,” Williams said of her program. “We need the community to trust us. I want to explain how we operate so we can build some of those bridges and build that trust which will help us all.”

Williams’ office declined to release a full list of community partners that have signed on to participate so far, citing confidentiality concerns, but said the organizations range from small businesses to multinational corporations and include local hospitals, schools, and regional sports and tourist venues. The group had a brief introductory meeting over Zoom last month.

Among them was the Jewish Federation of Greater Philadelphia, a fund-raising and grant-making organization that serves as a central convener for Jewish congregations and organizations throughout the region, many of which have expressed concern about a recent rise in anti-Semitic threats.

“We’ve seen an uptick in people sending anonymous stuff,” said Frank Riehl, the federation’s security director. “I think a lot of it has to do with the anonymity of being able to do that through a website, and I think with the [pandemic] lockdowns, people have a lot more time to think about these things and act on it.”

Riehl said his organization has already benefited from the type of collaboration Williams’ TIP Network hopes to foster. Last year, several of the federation’s affiliated organizations became the target of Zoom bombings, incidents in which internet trolls hijacked religious services with anti-Semitic remarks.

He contacted the FBI seeking guidance on who might be behind the incidents, how seriously they should take the threats, and for tips to better shore up security.

“You don’t want to take anything too lightly,” Riehl said. “But you can’t spend your entire day tracking all this down or you’ll go crazy. That’s why I think this organization is so important.”