Investigators have interviewed Minnesota Rep. Ilhan Omar’s sister, Sahra Noor, according to a law enforcement source familiar with the matter.

It comes as the Justice Department is investigating the Democratic congresswoman, focusing on immigration fraud related to suspected false statements made on government paperwork and a potential conspiracy, CNN previously reported.

The Trump administration had pushed for an unusually aggressive search of Omar’s house before a federal magistrate judge limited how the Justice Department could access her documents.

Investigators who obtained a warrant to search Omar’s Washington, DC, home on October 12 were looking into whether the congresswoman or her now-deceased father lied about her age when she obtained citizenship in 2000, people familiar with the investigation told CNN.

Investigators are probing whether the citizenship documents said she was a minor when she wasn’t.

Omar emigrated to the US as a Somalian refugee around the age of 12 and became a citizen in 2000, according to people familiar with Omar’s situation.

Applying for citizenship as a minor can streamline the process.

CNN has reached out to lawyers for Omar and attempted to reach Noor for comment.