The president and CEO of a major medical system in Maryland resigned Friday following revelations of numerous questionable financial arrangements involving board members, including Baltimore's embattled mayor.

Robert Chrencik had led the University of Maryland Medical System since 2008 before being sent on a leave of absence in late March. He departed on the requested leave amid embarrassing allegations of "self-dealing" involving members of the $4 billion hospital system's volunteer board. About one third of them received compensation through the network's murky arrangements with their businesses, ranging from pest control to insurance and management consultation.

One of the state's largest private employers, the university-based medical system did not explain why Chrencik was asked to go on leave or why he stepped down. But they described his resignation as "an important step in moving the health system forward during this critical time" and thanked him for his 35 years of executive employment at UMMS.

Baltimore Mayor Catherine Pugh has become the public face of the UMMS scandal after selling $500,000 worth of her self-published children's books to the hospital network. As a state senator before becoming mayor in 2016, Pugh had sponsored and co-sponsored several bills that would've benefited the medical system.

Chrencik's resignation comes a day after UMMS disclosed that the medical system received a grand jury witness subpoena seeking documents and information related to Pugh. Earlier Thursday, FBI and IRS agents raided her homes and City Hall offices amid dramatically widening investigations into her financial dealings.

In mid-April, Maryland Gov. Larry Hogan signed fast-tracked legislation to overhaul the UMMS board of directors, which oversees a system with roughly 25,000 workers and 4,000 affiliated physicians. Among other things, the new state law bars board members from getting contracts without a bidding process and prohibits board members from leveraging their position on the board for personal gain.