The district director for sophomore Democratic Rep. Tony Cárdenas notified the House Thursday that she’s been subpoenaed by a federal grand jury conducting an investigation in the U.S. District Court for the Central District of California.  

Gabriela Marquez, who heads operations in the Los Angeles congressman’s district office, issued the formal notice in accordance with House rules. It was read on the House floor on April 16. “The House received a communication from Gabriela Marquez, district director for the Hon. Tony Cardenas. Pursuant to Rule VIII of the Rules of the House of Representatives, Ms. Marquez notified the House that she has received a grand jury subpoena issued by the United States District Court for the Central District of California, and that after consultation with the Office of General Counsel regarding the subpoena, she will make determinations required under Rule VIII,” Joe Novotny, a reading clerk, read on the House floor.  

Staff in Cárdenas’ Washington, D.C., office confirmed Marquez’s letter, but declined multiple requests to provide further details.  

Yet sources in California told CQ Roll Call the FBI spent a few hours interviewing Marquez in her home roughly three weeks ago. According to a source, the FBI asked questions about whether staffers in Cárdenas’ office worked on campaign-related activities while being paid for official office time.  

Justice Department spokesman Peter Carr, citing agency policy, would neither confirm nor deny an investigation.  

Using official staff for political work could violate both federal appropriations law and House rules.  

The House Ethics Committee in 2012 fined former Rep. Laura Richardson, D-Calif., $10,000 for “requiring or compelling” her House office staffers to work on her campaign. The House subsequently voted to reprimand Richardson, who went on to lose her bid for re-election to now-Rep. Janice Hahn.  

Last month, the Los Angeles Daily News reported  Cárdenas’ wife and stepdaughter received a combined $120,000 for work on Cárdenas’ 2014 re-election bid — in which he defeated a little-known GOP challenger by a wide margin. But members of Congress are allowed to employ family members for jobs on campaigns, and his office denied any impropriety, according to the report.  

Cárdenas is a well-known name in Los Angeles.  

He began his political career in 1996, when he was elected to the state Assembly. He went on to win a seat on the Los Angeles City Council in 2003, after he was termed out of the state legislature.  

Cárdenas spent a decade on the council before ascending to Congress in 2012 in the 29th District — a new seat created in the 2010 redistricting process. Located in and around the Eastern San Fernando Valley, it’s a majority-Hispanic seat President Barack Obama carried with 77 percent of the vote in 2012.  

He is a member of the Congressional Hispanic Caucus, where he currently chairs BOLD PAC — the CHC’s fundraising arm that seeks to support Hispanic candidates for office.  

Correction 7:13 p.m. An earlier version of this post misstated the margin of victory Obama had in the district in 2012.