ORLANDO, Fla. -- Channel 9 learned Tuesday that the Florida Department of Law Enforcement (FDLE) took key evidence to an Orange County grand jury investigating Orlando city hall. That key evidence includes an incriminating e-mail written by the Orlando fire chief.

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The city hall investigation encompasses a number of allegations of wrongdoing during the most recent elections, including the mayor's race. A source close to the investigation told Channel 9 investigators have found the e-mail they were looking for from Fire Chief Bob Bowman directing a subordinate to alter a public record.

The subject of the email was about paying union firefighters who were campaigning for Mayor Buddy Dyer.

Tuesday, the grand jury heard from the lead investigator and three fire department employees.

It's illegal for anyone to discuss what goes on behind the closed doors of a grand jury proceeding. Tuesday's first witness, FDLE's lead investigator into the city hall elections, wouldn't even talk to us about the status of his investigation.

The grand jury also heard testimony from three fire department employees, including Deputy Chief Kathy Miller.

Miller's computer, Bowman's computer and the computers of two fire department financial managers were taken by FDLE to investigate whether some payments Bowman made to union firefighters were illegal.

Bowman somehow shortchanged a special union account provided for in the union contract for union business. Rather than dip into the city reserves and admit he was over budget, Bowman paid the union firefighters for campaigning for the mayor and other union business from another account.

The grand jury is investigating whether that was against the law. But what could hurt Bowman more is the e-mail we're told investigators found in city hall computers that came from him and was sent to an employee, directing the employee to change a public document to hide the unorthodox payments.

FDLE is also investigating one of Mayor Buddy Dyer's political consultants, who is a longtime League of Voters volunteer. Dyer's paid consultant, Ezzie Thomas, helps deliver voters' absentee ballots. But FDLE is investigating whether he actually cast their votes.

Dyer and Thomas deny it.

It's unclear if or when the grand jury will hear FDLE's evidence about the absentee ballots.

"We've collected as much information as we can and it's gonna be up to Mr. Lamar to decide what he needs in order to have the grand jury make their decision," says FDLE attorney Steve Brady.

The 21-member grand jury will meet again Wednesday to continue its investigation into the city hall elections.