More details have emerged about a pre-dawn raid earlier this week on the house of an outspoken critic of US President Donald Trump.
It is understood that the Trump administration is aiming to build a case to strip Minnesota representative Ilhan Omar of her US citizenship, according to sources familiar with the case.
Mr Trump has denied being involved in the raids, while ratcheting up insults against Ms Omar's origins.
Ms Omar, born in Somalia, became a naturalised US citizen in 2000.
Here's how the case could evolve.
What do we know about the investigation so far?
Homeland Security Investigations (HSI), carried out a search on Ms Omar's Washington DC home on Monday, local time.
HSI agents could be seen removing boxes labelled "Seized Property Evidence".
It is now understood there are several probes facing Ilhan Omar. (Reuters: Annabelle Gordon)
It is now understood the seized items included Ms Omar's phone and that more than a dozen grand jury subpoenas have been issued.
These subpoenas extended to some of Ms Omar's relatives.
US media reported the HSI probe is focused on how Ms Omar obtained her citizenship, and whether her father lied about her age when obtaining citizenship.
The sealed warrant listed conspiracy, false statements on immigration paperwork and immigration fraud as potential crimes, one person familiar with the case told Reuters.
The US Attorney's office is investigating Ms Omar's financial disclosures alongside the immigration probe, US Attorney Jeanine Pirro told Fox News.
"There are several investigations going on" Ms Pirro said.
Ms Omar's finances have previously been scrutinised because her husband, Timothy Mynett, owns stakes in two companies.
Ilhan Omar has called the raids an "outrageous abuse of power". (AP: J. Scott Applewhite)
Ms Omar's office denied wrongdoing and labelled the raid an "unprecedented escalation in the weaponization of federal law enforcement to target political enemies."
The raid occurred during Ms Omar's final weeks of a re-election bid, as a Democrat frequently targeted by Mr Trump and a member of the "squad", a group of young congresswomen of colour including Alexandria Ocasio-Cortez.
"No president should be able to use the power of the federal government to intimidate his political enemies," her office said on X.
Mr Trump denied knowledge of the investigation, but later emphasised her Somali origins at an Ohio rally.
"She's telling us about the Constitution, and she comes from one of the worst countries anywhere on the planet," Mr Trump said, as the crowd shouted, "deport".
Ilhan Omar's association with the "squad" has often put her into the firing line of Donald Trump. (Reuters: Evelyn Hockstein)
How did Ilhan Omar become a citizen?
Ms Omar and her family fled Somalia as refugees after the country descended into civil war.
They came to the US in 1995.
She became eligible for citizenship in 2000.
US media reports the investigation is determining whether her father lied about her age on the application, writing she was 17 rather than 18.
If Ms Omar was 18, she would be responsible for her own immigration process.
Ms Omar's campaign previously told AP she and others cannot get birth certificates because Somalia's infrastructure collapsed during the civil war.
Since 2016, she has also faced speculation she married her brother.
No proof emerged to support these claims, despite Mr Trump repeating them.
In 2018, The Minneapolis Star Tribune reported Ms Omar showed a reporter phone images of documents from her family's entry into the US.
They listed her father and siblings in birth order, with Ms Omar listed as the youngest of seven children.
Her first husband's name, Ahmed Nur Said Elmi, did not appear in the documents.
According to the couple's marriage certificate, he is also three years younger than Ms Omar, whose mother died when she was two years old.
The Obama administration declined to investigate these claims at the time.
During her tenure, Ms Omar has faced death threats and being sprayed with vinegar. (Reuters: Maria Alejandra Cardona)
The state of deportation in the US
The Homeland Security threat of deportation is real to many Somali-Americans.
In Ms Omar's case, this would occur as denaturalisation, in which citizenship is revoked, though the Justice Department must file a lawsuit proving the person lied in a material way during their application.
Last week, Attorney General Todd Blanche boasted of the "largest denaturalisation effort in modern history" after the Justice Department filed 40 cases.
In Mr Trump's second term, the justice department has filed at least 164 denaturalisation cases.
The Trump administration has cracked down on naturalisation, with denial applications more than doubling between May 2024 and May 2026, according to the National Foundation for American Policy.
The American Civil Liberties Union accused the administration of "embarking on the largest de-legalisation campaign our nation has seen in generations" and of targeting " Black and Brown citizens".
The Trump administration previously terminated Temporary Protected Status for Somalis, though a court challenge is underway.
ABC/Wires