Investigators suspected Mr Pagano had paid himself an improper "bonus"
The chief of the Chicago commuter rail system has killed himself by stepping in front of a speeding train, officials have said.
Philip Pagano was under investigation over alleged financial irregularities and was on paid leave.
The board of the Metra system had been due to meet later on Friday to determine his fate.
In his pocket, police found a manual detailing procedures for handling a suicide on the railway, officials said.
Mr Pagano had been executive director of the Metra system, which serves the city of Chicago and its outlying suburbs, since 1990.
State prosecutors and federal officials had launched investigations into whether Mr Pagano had improperly steered public funds to his personal coffers.
Metra officials said last month that Mr Pagano had received an unauthorised $56,000 "bonus" in addition to his $269,625 salary. The agency does not award bonuses.
The Chicago Tribune reported that Mr Pagano had stepped in front of a Metra train in the suburb in which he lived, north-west of Chicago.
McHenry County Coroner Marlene Lantz told the paper the death was under investigation, "but at this point it appears to be a suicide".