Federal agents seized Democratic Rep. Ilhan Omar’s phone when they searched her Washington, D.C., home this week as part of a federal investigation into potential immigration-related crimes, and have sent roughly a dozen subpoenas out in the case, according to two people familiar with the investigation.

The possible charges cited by federal officials included conspiracy and making false statements in immigration paperwork, one of the people said.

The search came just three weeks before the midterms, within the window of time when the Justice Department has typically avoided overt actions in criminal cases that could affect an election. And the seizure of the phone of a sitting member of Congress would typically trigger a set of law enforcement protocols meant to ensure investigators aren’t infringing upon the “speech or debate” clause of the U.S. Constitution, which protects members of Congress from being questioned for their legislative acts.

On Friday, roughly a dozen subpoenas were sent out in the case, including to her family members, the second person familiar with the investigation told NBC News.

The congresswoman herself was not subpoenaed, the person said, adding that the orders seeking information are tied to a federal grand jury in Minnesota, Omar’s home state. Federal agents also want to talk to Omar’s sister but haven’t reached her yet, the person said.

The New York Times first reported the subpoenas.

The investigation is being conducted by Homeland Security Investigations, the U.S. attorney in Minneapolis and the Justice Department.

A spokesperson for Omar didn’t respond to a request for comment. The Justice Department declined to comment.

Omar said in a statement posted online on Monday that she would not be silenced.

“Make no mistake: this is an attempt to target political enemies and weaponize federal law enforcement. For ten years, Trump has targeted me with baseless lies and smear campaigns. This is just the latest escalation in his campaign of political intimidation,” she wrote.

One of the people familiar with the investigation said it involved whistleblowers, documents and witness testimony. The probe is examining matters surrounding Omar’s immigration status, including — but not limited to — her birthdate. Omar, who was born in Somalia and moved to the United States with her family in the 1990s, was naturalized when she was 17 years old, meaning she was a juvenile and could be conferred citizenship through a parent.

A criminal investigation could be complicated by the statute of limitations, which is typically five years, but investigators could look into Omar’s or her family members’ more recent actions that would fall within the statute of limitations.

Omar, who is part of a group of progressive women in Congress known as “the Squad,” has been a frequent target of Trump’s rhetoric against her and other members’ liberal positions, as well as Somali immigrants broadly.

Asked Monday if he had been aware of the search in advance, Trump said the federal government was looking at Omar “very carefully.” He also repeated his frequent attacks on her and Somalia.

“Then she comes over here and she complains about our Constitution,” Trump said. “I think she’s a terrible person, but that’s really up to the DOJ.”

That evening, Trump also attacked Omar in remarks at a rally he held for Republicans in Ohio.

“I don’t know what they’re doing with it, but I can tell you this: She’s a disaster,” Trump said. “She comes in from a country without laws, without police, without military, where all they do is shoot each other, and she comes into our country and she says, ‘I have a constitutional right.’”

Homeland Security Secretary Markwayne Mullin appeared to tease federal action against Omar last month when he said “something’s going to happen” with her, but they were still investigating.

“If we actually move a case forward, it’s not a political case,” Mullin said. “It’s an actual case because they did things wrong. If you decided to break the law or lie [about] the information you gave the United States to be able to come into the United States through either asylum or because you were just wanting to seek a better life, but you didn’t tell us who you actually were, you lied about certain things about your application — those things, there’s no expiration to that.”