Former New Orleans Mayor Ray Nagin, the colorful and controversial spokesman for the city after the devastating Hurricane Katrina in 2005, is under investigation by federal authorities, a source with direct knowledge of the probe said.

The source told Reuters on Friday that several people linked to Nagin or the New Orleans city administration during his two terms as mayor ending in 2010 were cooperating with the U.S. Justice Department and the FBI.

The investigation includes whether Nagin received favors or items of value from vendors to the city in return for contracts they received while Nagin was in office, the source said.

Read more: Former New Orleans Mayor Ray Nagin under investigation