The Georgia Bureau of Investigation has completed its criminal investigation of state Sen. Don Balfour, R-Snellville, on allegations he filed false expense reports, although state Attorney General Sam Olens remained mum Thursday on the outcome.

A spokeswoman for Olens confirmed to The Atlanta Journal-Constitution that his office had Balfour’s case file but would have no other comment.

Olens and his staff received the file Dec. 14, GBI spokesman John Bankhead said.

The GBI’s involvement marked the first criminal investigation of a state senator since 2005, when then-Sen. Charles Walker was convicted in federal court on 127 counts including mail fraud, tax evasion and conspiracy.

Balfour, who is expected next week to lose his position as chairman of the Senate’s powerful Rules Committee, has repeatedly said he inadvertently made mistakes on expense reports going back to at least 2009.

The case followed an unusually public rebuke of Balfour last year by the Senate Ethics Committee, which fined Balfour $5,000 for filing inaccurate travel reports to claim expenses. Balfour was also told to repay about $350 to the state for the lapses.

The work seemed to light a fire about ethics in the chamber, since the committee this year has spearheaded efforts for the Senate to self-impose a $100 limit on gifts by lobbyists to senators.