The Federal Bureau of Investigation said in a statement Wednesday evening that it is conducting a "court-authorized" search of the Texas home of Representative Henry Kueller, a moderate Democrat.
CNN has learned that the FBI also searched another building in his campaign office.
"The FBI was conducting court-authorized law enforcement activity around Windridge Drive and Estate Drive in Laredo," an FBI spokesman said in a statement. "The FBI cannot provide further comment on the ongoing investigation."
The Justice Department's Public Integrity Unit is involved in the investigation, a source familiar with the matter told CNN. The Public Integrity Section handles matters involving elected officials, including campaign finance and other investigations.
A spokesman for Cuellar told CNN that "Congressman Kueller will fully cooperate with any investigation. He is committed to ensuring that justice and the law are upheld."
Kueller has served in the 28th Congressional District of Texas since 2005. He has not voted in person at the Capitol since January 12. He currently has an active proxy letter, which allows another MP to vote for him in person in the House.
This news was first reported by The Monitor newspaper.
Valerie Gonzalez, a reporter with the Monitor, explained in a tweet Wednesday evening that "around 7:30 p.m., a group of agents loaded large bags, plastic bins and a computer into a federal vehicle. Others would log items." appeared."