Griffith sent a letter Tuesday to U.S. Attorney General Eric Holder decrying the inquiry into former Democratic state Sen. Phil Puckett's resignation last month.
Prosecutors have subpoenaed records related to a potential job offer at a GOP-controlled tobacco commission Puckett was considering at the time of his resignation.
Puckett's departure from the upper chamber gave Republicans control of the state Senate and dealt a blow to Gov. Terry McAuliffe's bid to expand Medicaid.
Griffith, a Republican, said he does not think Puckett did anything wrong. He said the investigation appears to be intended to intimidate law-abiding individuals.
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