Federal authorities investigating Minnesota Rep. Ilhan Omar seized the Democratic lawmaker’s phone and have issued more than a dozen grand jury subpoenas, including to some of her relatives, according to a person briefed on the probe.

The subpoenas were issued for a grand jury collecting evidence in Minnesota as federal authorities probe potential fraud in Omar’s immigration paperwork, said the person, who spoke on the condition of anonymity because they were not authorized to discuss an ongoing investigation. The investigation led to federal agents searching Omar’s Washington, D.C. home on Monday just weeks before the November midterms, in which Omar is seeking reelection.

The scope of the investigation into Omar is unclear, though Homeland Security Secretary Markwayne Mullin has suggested that authorities were examining potential crimes related to her family’s immigration paperwork.