Doyle said she requested the investigation after a meeting with town officials and reviewing documents.
The DA did not name any employees or give additional information.
In May, the Smithfield Town Council voted unanimously to fire town manager Eric Williams. He had already been placed on administrative leave and an interim town manager was appointed.
Williams had been at the center of a pay raise controversy. According to documents obtained by ABC11, Town Clerk Debra Godwin received a 29 percent raise and Public Works Director Lenny Branch was given a 17 percent hike even though the increases had not been approved by the town council.
Williams maintains he didn't give the okay for the salary increases.