ABC News April 25, 2019

FBI agents search homes and office of Baltimore's embattled mayor Catherine Pugh

WATCH: News headlines today: April 25, 2019

FBI agents are searching the office and homes of Baltimore's embattled mayor, ABC News has learned.

Dave Fitz, a spokesman for the FBI's Baltimore field office, confirmed that search warrants were being executed Thursday morning at homes belonging to Mayor Catherine Pugh as well as at Baltimore City Hall. However, the nature of the investigation and substance of the searches are under seal.

Charles Krupa/AP, FILE
Baltimore Mayor Catherine Pugh addresses a gathering during the annual meeting of the U.S. Conference of Mayors in Boston, June 8, 2018.

The mayor's office did not immediately respond to ABC News' request for comment.

(MORE: Jane Castor elected Tampa's first openly LGBTQ mayor)

Pugh is on a leave of absence due to deteriorating health from a bout with pneumonia. The mayor announced her departure earlier this month, on the same day Maryland Gov. Larry Hogan called for a criminal investigation into Pugh's lucrative book sales to the University of Maryland Medical System while she was a board member.

Lloyd Fox/Baltimore Sun via AP
Federal agents arrive at the Maryland Center for Adult Training in Baltimore, Md., April 25, 2019. Agents with the FBI and IRS are gathering evidence inside the two homes of Baltimore Mayor Catherine Pugh and in City Hall, as well as the office of her lawyer and the home of a top aide.

Pugh has since stepped down from her board position and returned $100,000 to the medical system for the last order of her self-published children's book, "Healthy Holly," according to ABC Baltimore affiliate WMAR.