In a Minnesota courtroom more than a decade ago, federal prosecutors said Salah Osman Ahmed had helped the US government.

A judge was about to decide the former security guard’s fate, 14 years after he’d immigrated to Minnesota, four years after he’d pleaded guilty to providing material support to terrorists, and seven months after he’d taken the stand as a cooperating witness in a high-profile trial.

On a morning in May 2013, when it was time for a decision in Ahmed’s own case, prosecutors cited his “substantial assistance” and recommended a reduced sentence.

“Mr. Ahmed’s post-arrest candor, I think, was very important,” prosecutor William Narus told a judge as he described the rationale behind the government’s request.

But in a lawsuit filed this year in the same court, a different team of federal prosecutors painted a harsher picture of Ahmed. The 44-year-old’s US citizenship should be revoked, they argued, because of the months he spent as an al-Shabaab recruit in Somalia in late 2007 and early 2008.

“Defendant’s material support for this terrorist group so shortly after he gained citizenship establishes that when he naturalized, he lacked the requisite attachment to the principles of the Constitution and dedication to the good order and happiness of the United States,” the suit states. Now once again, it will be up to a judge to decide Ahmed’s fate.

The case against Ahmed is part of what Attorney General Todd Blanche bills as “the largest denaturalization effort in modern history.”Researchers say more than 170 civil denaturalization lawsuits have been filed since President Donald Trump’s second term began.

But several details about this Minnesota case make it different from others on the docket, according to experts who spoke with CNN. It could have far-reaching implications in other terrorism cases, they say, and signals the government is now willing to invoke portions of the law that haven’t been used before as part of its widening denaturalization campaign.

“This is important beyond just this one case,” says Irina Manta, a visiting professor at Villanova University’s Charles Widger School of Law who studies denaturalization. “I really think they are testing the limits here.”Revoking someone’s citizenship returns them to the immigration status they had before naturalization. That potentially makes them vulnerable to deportation proceedings, if the government decides to pursue another case in immigration court.

White House deputy chief of staff Stephen Miller has called denaturalization a “turbocharged” priority. But the process is still relatively rare — and difficult by design.

In civil denaturalization cases, the government must provide “clear, unequivocal and convincing evidence,” and a federal judge has the final say.

So far, fewer than 200 civil denaturalization cases have been filed since January 2025 — a minuscule fraction of the estimated 26 million naturalized American citizens. But the number of lawsuits filed under this administration is significantly higher than any other recent presidency. Federal prosecutors have filed more this year alone than the total number previously filed over the course of nearly two decades, according to an analysis by the Transactional Records Access Clearinghouse of case filings through September 28, 2026.

A recent raid on Rep. Ilhan Omar’s DC-area home as part of what sources describe as an immigration-fraud probe brought increased attention to the administration’s intensifying focus on denaturalization. The Justice Department has not revealed any evidence against Omar or indicated it would take steps to denaturalize the Minnesota congresswoman. She has not been charged with any crime and denies any wrongdoing.

Even before the raid at her house made headlines, officials have been picking up the pace in their denaturalization efforts for months.

“Individuals implicated in committing fraud, heinous crimes such as sexual abuse, or expressing support for terrorism should never have been naturalized as United States citizens,” Blanche said in a May press release detailing the cases against Ahmed and 11 other defendants. “The Trump administration is taking action to correct these egregious violations of our immigration system.”Like many of the civil denaturalization lawsuits filed so far, the case against Ahmed targets someone with a serious criminal conviction. He was sentenced to three years in prison for his admitted support of terrorists. Other recent denaturalization cases announced by the government have targeted convicted child molesters, fraudsters and spies.

But according to Ahmed’s lawyer, the denaturalization case against his client is “shameful” — and glosses over significant details.

“He helped them put together their terrorism case,” attorney Daniel Gerdts told CNN. “Their reward for him doing that is to take away his citizenship. That makes us look terrible as a nation.”Ahmed, who declined to comment to CNN through his attorney, said in earlier court proceedings that he came to the United States when he was 15 years old. He became a US citizen as a 24-year-old in August 2007, according to court records. And four months later, according to court documents, he was on a flight bound for Somalia to join al-Shabaab’s fight against Ethiopian troops who had invaded his home country the previous year.

“To be honest, I don’t know what I was thinking,” Ahmed testified in 2012, “but I said, ‘OK, let’s go, let’s stop the Ethiopians taking over the country.’”He spent time in an al-Shabaab safe house, raised funds, underwent some weapons training and helped clear land for a training camp, then fled after several months and returned to the US, according to court records.

Federal agents arrested Ahmed in July 2009 as part of an investigation into the recruitment pipeline that was funneling youth from Minnesota’s Somali immigrant communities into al-Shabaab. He pleaded guilty later that month to providing material support to terrorists, admitting he’d engaged in a criminal conspiracy to kill Ethiopians.

In 2012, Ahmed was a cooperating witness in the trial of Mahamud Said Omar, a mosque janitor who was convicted and later sentenced to 20 years in prison for his role funneling money to al-Shabaab and recruiting fighters for the terrorist group from the Twin Cities.

During Ahmed’s 2013 sentencing hearing, the prosecutor said Ahmed had committed a serious crime, but he also noted that Ahmed’s decision to leave al-Shabaab was “commendable,” according to a transcript of the proceedings. Of all the defendants prosecuted in the investigation, Narus said, Ahmed had made “the cleanest break” away from the terrorist organization.

“I don’t want to be a terrorist. I didn’t sign up and I will never be — that’s one of the reasons I left,” Ahmed told the judge that day, adding that he was thankful to be in court and vowing to be a better man.

“I’m so grateful that I am speaking and have life to be in the United States. I’m so grateful and I will never want to lose that,” he said.

If the denaturalization case against him succeeds, Ahmed’s days in the US could be numbered.

But in an August court filing, his lawyer denied the accusation that Ahmed “lacked the requisite attachment to the principles of the Constitution” when he became a US citizen. In a response pushing back on many of the government’s justifications for revoking Ahmed’s citizenship, Attorney Daniel Gerdts argued that Ahmed had travelled to Somalia before the US government officially designated al-Shabaab a foreign terrorist organization, and that he was never a member of the group. Gerdts also argued the government should be blocked from seeking denaturalization now given that previously “it praised and rewarded Defendant’s substantial contributions to the national security and law enforcement of the United States.”Ahmed’s attorney isn’t the only one concerned about that facet of the case.

Revoking a cooperating witness’ citizenship and making them vulnerable to deportation could have far-reaching implications beyond this case, a former federal law enforcement official who’s worked on similar counterterrorism cases in the past told CNN.

Other potential cooperating witnesses in terrorism cases would be far less likely to agree to help the US government in the future, according to the former official, who asked not to be identified because they feared retaliation for speaking out.

“The wrong thing is happening here,” the former official said. “Nobody’s going to cooperate. This is so short-sighted just as a policy matter that it’s totally counterproductive to our national security.”

If denaturalization and deportation are on the table, the calculus will be different for would-be witnesses weighing whether to testify against terrorist organizations that are still active in their home countries, the former official said. “Probably you won’t do it, because you’ll get killed.”Asked about Ahmed’s case and concerns that trying to strip citizenship from a cooperating witness could have a broader impact, a Department of Justice spokesperson reiterated officials’ commitment to pursuing denaturalization cases.

“The Department of Justice follows the facts and the law in each case,” the spokesperson said in a statement. “The Department’s denaturalization efforts are historic and remain a top priority for this administration.”

Moving to denaturalize a cooperating witness aligns with the “scorched earth policy” on immigration that the second Trump administration has adopted, according to Wadie Said, a law professor at the University of Colorado and author of “Crimes of Terror: The Legal and Political Implications of Federal Terrorism Prosecutions.”“It just strikes me as a really poor exercise of judgment,” he said.

This isn’t the first time officials have tried to revoke the citizenship of a cooperating witness. Prosecutors previously pursued a denaturalization case against a woman who’d helped investigators in a fraud case against her employer, according to Cassandra Burke Robertson, a law professor at Case Western Reserve University.

“She cooperated in making the case against her boss. And then the first Trump administration, after she had pleaded guilty and served the probation, used that as a rationale to strip her citizenship,” Robertson said.

The question isn’t whether the government can move to denaturalize a cooperating witness, but whether it should, according to CNN Chief Law Enforcement and Intelligence Analyst John Miller.

“It’s not a question of technicality. It’s a question of equity. Is it the right thing to do?” said Miller, who previously served as the New York Police Department’s deputy commissioner of intelligence and counterterrorism and as an assistant director of the FBI.

Cooperating witnesses often play an essential role in terrorism cases, Miller said.

“You can only get so far with undercover videos and undercover operators and undercover tapes,” he said. “There’s nothing like a live witness who was a part of that conversation or a part of that group or a part of that plot.”Word that the government is targeting a cooperating witness is likely to spread, Miller said.

“You have to ask yourself, ‘Why are we doing this, and what’s the effect going to be on future cooperators?’ It is an insular community. And word will get around,” he said.

It could be months or even years before the case against Ahmed makes its way through the court system. But already it’s catching the attention of some scholars and advocates. The legal argument authorities are making is one reason why.

Most denaturalization cases focus on crimes committed before someone becomes a citizen, or on alleged fraud during the naturalization process. In this case, authorities are arguing that Ahmed’s citizenship should be revoked because of conduct that allegedly occurred after he became an American.

To do that, they’re invoking a McCarthy-era provision of the law that’s rarely, if ever, been used, said Manta, the Villanova visiting professor. The provision will likely face legal challenges over its constitutionality, she said.

“As far as I’m aware, there has actually never been a case that relied solely on this provision … No government, no regime has been aggressive enough to try it,” Manta said. “But this regime has announced that it wants essentially quotas of how many people it’s going to denaturalize. So, when you have a quota, you’re going to try to find anything and everything … to find cases that maybe otherwise wouldn’t have been able to fly.”

Naturalization laws block someone from obtaining US citizenship if they are affiliated with certain organizations, including the Communist Party or any groups that advocate violently overthrowing the US government or “the unlawful damage, injury, or destruction of property.”The provision invoked in Ahmed’s case states that if someone joins or affiliates with such organizations within five years after naturalization, it’s seen as evidence that they weren’t “attached to the principles” of the US Constitution when they became citizens.

The Justice Department hasn’t responded to questions from CNN about its use of the provision in this case, or whether officials have plans to use it in additional prosecutions. So far, according to a denaturalization case tracker from the advocacy organization Democracy Forward, available court records show Trump administration officials are citing this provision in two cases: Ahmed’s and a Missouri denaturalization case against a man who pleaded guilty to providing material support to al Qaeda.

But some advocates say they’re concerned the provision could be applied more broadly in the future, applying not only to a rapidly growing number of designated terrorist groups, but also to others accused of endangering national security or being enemies of a presidential administration. It’s possible, they say, that political opponents could one day find themselves on the receiving end of a denaturalization lawsuit.

“No one can or should be denaturalized for engaging in political conduct that this administration disagrees with. But this administration may try,” said Steven Salky, an attorney who is helping to track denaturalization filings and creating a clearinghouse to match cases with pro bono lawyers.

Using post-naturalization conduct to allege earlier disloyalty could have a chilling effect, Manta said, making naturalized Americans fear that what they say and who they associate with could be used against them.

Already, she said, the recent raid targeting Omar has intensified concerns about “weaponization of denaturalization and silencing of political speech.”“People have been naturalized for years, have done nothing wrong, have no reason to believe that the government would find anything legitimately that they did wrong, and still, they’re afraid,” she said.

But some see the recent case against Ahmed as a reminder that denaturalization laws aren’t tough enough.

In June, a Michigan congressman cited the case when announcing a proposed law that would automatically denaturalize someone convicted of terror-related charges.

“Under current law, a naturalized citizen cannot be removed even for the most violent acts of terror without first going through the slow and complex denaturalization process. This loophole has allowed individuals who embraced terrorist ideologies after gaining citizenship to remain shielded from swift removal,” a statement from Rep. Bill Huizenga’s office said when he introduced his “Deport the Terrorists Act.”That measure remains in committee, but the Trump administration’s denaturalization push shows no signs of slowing.

So far, cases have been filed in at least 40 US states, the District of Columbia and Puerto Rico, according to data compiled by TRAC.

Researchers say the actual number of denaturalization cases could be higher than their latest estimates, as filings are difficult to track and obtain due to privacy restrictions. Officials have promised there are more cases to come.

“This administration will continue to pursue the largest denaturalization effort in department history,” Assistant Attorney General Brett Shumate said in a statement as the Justice Department announced a batch of 40 cases earlier this month, “to restore trust and integrity in U.S. citizenship.”And in the Minnesota District Court where Ahmed’s case will be heard, lawyers are already gearing up for a fight.

Federal prosecutors last week asked the judge assigned to the case to be disqualified from hearing it, arguing that because of comments he made to The New York Times about how courts were impacted by the government’s handling of Operation Metro Surge last winter in Minneapolis, he “cannot then preside over a case concerning one of the Justice Department’s key immigration initiatives.”A spokesperson for Minnesota’s US district court says the interviews judges gave to the Times were “well within the ethical rules that apply to federal judges.”And Gerdts says he plans to oppose the government’s “baseless” motion. A hearing over the matter is scheduled for next month.