By Jeff McKinney
Enquirer staff writer

HIGHLAND HEIGHTS - The FBI is investigating a possible case of bank fraud at Citizens Bank of Northern Kentucky.

The probe started after Mark Steffen, 27, a former assistant vice president and manager of a Citizens branch, died in an apparent suicide. He died of possible carbon monoxide poisoning at his parents' home in Highland Heights on or about Aug. 16, Campbell County Deputy Coroner Al Garnick said Thursday.

Steffen resigned Aug. 12, bank officials said. He had been with the bank about seven years.

He left a note stating he had committed some kind of fraud at the bank, Garnick said.

Bill O'Leary, supervisor at the FBI's Covington office, said his office is working with the Highland Heights Police Department on the case.

Steffen resigned from the bank to pursue other opportunities, said David Van Horn, Citizens president and CEO. "We thought the world of Mark, and we're just shocked by all of this."

Van Horn said Citizens is conducting its own investigation. He wouldn't say if any money is missing from the bank.

The Kentucky Department of Financial Institutions is also investigating.

E-mail jmckinney@enquirer.com