FBI agents took box after box of address books, family calendars, artwork and personal letters in their 10-hour raid in September of the century-old house shared by Stephanie Weiner and her husband.

The agents seemed keenly interested in Weiner’s home-based business, the Revolutionary Lemonade Stand, which sells silkscreened baby outfits and other clothes with socialist slogans, phrases like “Help Wanted: Revolutionaries.”

The search was part of a mysterious, ongoing nationwide terrorism investigation with an unusual target: prominent peace activists and politically active labor organizers.

The probe — involving subpoenas to 23 people and raids of seven homes last fall — has triggered a high-powered protest against the Department of Justice and, in the process, could create some political discomfort for President Obama with his union supporters as he gears up for his reelection campaign.

The apparent targets are concentrated in the Midwest, including Chicagoans who crossed paths with Obama when he was a young state senator and some who have been active in labor unions that supported his political rise.

Anti-war activist Tom Burke meets Barack Obama in 2004 at Burke's Chicago-area  union hall as Obama was running for U.S. Senate. Burke is one of 23 prominent anti-war activists to be subpoenaed as part of an ongoing FBI terrorism probe. (Courtesy of Tom Burke)

Investigators, according to search warrants, documents and interviews, are examining possible “material support” for Colombian and Palestinian groups designated by the U.S. government as terrorists.

The apparent targets, all vocal and visible critics of U.S. foreign policy in the Middle East and South America, deny any ties to terrorism. They say the government, using its post-9/11 focus on terrorism as a pretext, is targeting them for their political views.

They are “public non-violent activists with long, distinguished careers in public service, including teachers, union organizers and antiwar and community leaders,” said Michael Deutsch, a Chicago lawyer and part of a legal team defending those who believe they are being targeted by the investigation.

Several activists and their lawyers said they believe indictments could come anytime, so they have turned their organizing skills toward a counteroffensive, decrying the inquiry as a threat to their First Amendment rights.

Those who have been subpoenaed, most of them non-Muslim, include clerical workers, educators and in one case a stay-at-home dad. Some are lesbian couples with young children — a point apparently noted by investigators, who infiltrated the activists’ circle with an undercover officer presenting herself as a lesbian mother.

All 23 of the activists invoked their right not to testify before a grand jury, defying U.S. Attorney Patrick Fitzgerald, whose office is spearheading the investigation.

A spokesman for Fitzgerald, the Chicago prosecutor whose past work has sometimes riled both political parties, declined to comment.

It is uncertain whether Obama is aware of the investigation. A White House official referred questions to the Justice Department, where spokesman Matthew Miller said the agency will not comment on an investigation, but he disputed any assertion that people would be targeted for political activities.

“Whenever we open an investigation, it is solely because we have a reason to do so based on the facts, evidence and the law,”Miller said.

The activists have formed the Committee to Stop FBI Repression, organized phone banks to flood Attorney General Eric H. Holder Jr.’s office and the White House with protest calls, solicited letters from labor unions and faith-based groups and sent delegations to Capitol Hill to gin up support from lawmakers.

Labor backers include local and statewide affiliates representing the Service Employees International Union and the American Federation of State, County and Municipal Employees, two of the most influential unions in the liberal movement. So far, nine members of Congress have written letters to the administration asking questions.

The major national labor organizations have not gotten involved in the case and are considered likely to support Obama’s reelection next year.

But some state and local union organizations are expressing alarm about the case, saying that the government appears to be scrutinizing efforts by workers to build ties with trade unionists in other countries.

“I am so disgusted when I see that so many union people have been targeted in this,” said Phyllis Walker, president of AFSCME Local 3800, which represents clerical workers at the University of Minnesota, including four members who are possible targets.

The union’s statewide group, which says it represents 46,000 workers, called on Obama to investigate and passed a resolution expressing “grave concern” about the raids. Similar resolutions have been approved by statewide AFSCME and SEIU affiliates in Illinois.

If there are indictments, the case could test a 2010 Supreme Court ruling that found the ban on material support for designated foreign terrorist groups does not necessarily violate the First Amendment — even if the aid was intended for peaceful or humanitarian uses. The ruling held that any type of support could ultimately help a terrorist group’s pursuit of violence.

The probe appears to date from 2008, as a number of activists began planning for massive antiwar demonstrations at the Republican National Convention in St. Paul.

After the convention, the FBI’s interest continued, apparently focused on the international work pursued by many of the participants. Several activists said they had traveled to Colombia or the Palestinian territories on “fact-finding” trips designed to bolster their case back home against U.S. military support for the Israeli and Colombian governments.

In 2009, a group raised money to travel and deliver about $1,000 to a Palestinian women’s group, but the delegation was turned back by officials at the airport in Israel, organizers said.

Search warrants, subpoenas and documents show that the FBI has been interested in links between the activists and the Revolutionary Armed Forces of Colombia (FARC), the Popular Front for the Liberation of Palestine and Hezbollah.

In the early morning of Sept. 24, 2010, agents raided homes in Chicago and Minneapolis, issued subpoenas to 14 activists, and tried to question others around the country, including prominent antiwar organizers in North Carolina and California.

At 7 a.m., according to documents and interviews, about a dozen armed federal agents used a battering ram to force their way into Mick Kelly’s second-floor apartment, which sits over an all-night coffee shop in a working-class neighborhood of Minneapolis.

Kelly, 53, a cook in a University of Minnesota dormitory and a member of the Teamsters, said he was at work and his nightgown-clad wife, Linden Gawboy, was slow to answer the door.

Apparently by accident, the agents left something behind: a packet of secret documents headlined “Operation Order,” laying out detailed instructions for the FBI SWAT team to find clues of Kelly’s activism, including personal finances or those of the Freedom Road Socialist Organization, a far-left group he works with. The documents point to the FBI’s interest in Kelly’s foreign travel.

“We’ve done absolutely nothing wrong,” Kelly said. “We don’t know what this is about, but we know that our rights to organize and speak out are being violated.”

In Chicago, the raid at the home of Weiner, 49, also targeted her husband, Joe Iosbaker, 52, a University of Illinois-Chicago office worker and a union steward for his SEIU local. The couple are among the grassroots activists close to the world once inhabited by Barack Obama who have been caught up in the investigation.

Like others, Weiner and Iosbacker have been fixtures on the local liberal political scene, protesting police actions, attending antiwar rallies, leading pay equity fights and even doing some volunteer work for Obama’s past campaigns.

Tom Burke, who received a subpoena Sept. 24, had in 2004 discussed the plight of murdered Colombian trade unionists with then-state senator Obama.

“He was a sympathetic ear,” Burke said, recalling that Obama told him the murders were a “human rights problem.”

Hatem Abudayyeh, one of seven Palestinians to be subpoenaed in the investigation, recalls encountering Obama in the community during his years as a state legislator. Abudayyeh, 40, is executive director of the Arab American Action Network, a Chicago advocacy group that hosted then-state senator Obama for at least two events.

The role of the undercover officer, which defense lawyers said was confirmed in their talks with prosecutors, became clear in the weeks following the raids. She had joined a Minneapolis antiwar group, then joined demonstrations at the School of the Americas military training site in Fort Benning, Georgia, and at one point flying with a group to Israel on the trip that was thwarted at the airport.

“They were smart sending a 40-year-old lesbian,” said Meredith Aby, 38, a high school civics teacher and longtime organizer. “A good match,” added Jess Sundin, a university clerical worker.

Aby and Sundin, whose homes were raided and who received subpoenas, had helped lead a group called the Anti-War Committee that had coordinated with antiwar activists across the country to plan the demonstrations at the Republican convention.

Civil libertarians and other critics say the investigation fits a pattern for the FBI, pointing to a Justice Department inspector general’s report — issued three days before the raids — chiding the agency for monitoring the domestic political activities of Greenpeace, People for the Ethical Treatment of Animals and other groups in the name of combating terrorism.

Rep. Jan Schakowsky (D-Ill.), a member of the House Intelligence Committee and a close Obama ally, wrote Holder in April conveying the activists’ concerns that the probe was infringing on their rights.

“Clearly we need to have a bright line where people can exercise their civil rights, their civil liberties, to peacefully protest,” Schakowsky said in an interview.

Holder experienced the activists’ anger first hand last month, when Tracy Molm, 30, an AFSCME organizer whose apartment was raided, stood to interrupt a speech he was giving at the University of Minnesota. Holder, unaware that she was a possible investigation target, agreed to meet with her after the speech.

In a small room off the auditorium, with the attorney general flanked by aides and security, Molm demanded to know why the administration was pursuing the inquiry, she recalled later in an interview.

“He said they had a predicate for the investigation,” Molm said. “I said, ‘The predicates after 9/11 are nothing.’”

“We’re going to have to agree to disagree,” Holder replied, according to Molm.

At that point, Molm revealed that her apartment had been raided as part of the investigation. Holder and Justice Department officials abruptly ended the discussion.