A subpoena obtained by The Associated Press shows a federal grand jury is looking into loans made to Kansas Gov. Sam Brownback’s re-election campaign.

The subpoena orders the executive director of the Kansas Governmental Ethics Commission to appear Wednesday in Topeka and to provide documents pertaining to loans Brownback’s campaign received in 2013 and 2014.

The Dec. 2 subpoena doesn’t say which specific loans are being investigated, but the only loans listed on campaign disclosure reports for those years are one from Brownback himself and others from Lt. Gov. Jeff Colyer.

Colyer loaned Brownback’s campaign $500,000 in August, the third such loan Brownback’s running mate made to the governor’s re-election bid.

The governor’s office said Thursday that it was unaware of the investigation. The U.S. attorney’s office declined comment.