Jack Abercia had been Precinct 1 constable since 1991.
That tenure came to an abrupt end Thursday when federal officials arrested him and two of his top officers.
The indictment includes charges of bribery, conspiracy and running illegal background checks.
The commissioners appointed Ken Berry to be the new constable until the next election.
Here's County Judge Ed Emmett:
"Let's face it, this is a tragic set of circumstances for a lot of people concerned. But the importance of Precinct 1 Constable with all the things they do downtown, and particularly mental health warrants and things like that, we need somebody to step in and that's why we had to do the emergency session today. I'm just thankful Ken Berry was available."
Berry served 35 years with the sheriff's office, retiring as a major.
"They can feel confident that I didn't just walk into law enforcement. I'm quite familiar with law enforcement and what's needed to be done."
He says he's ready to take up his duties, despite the ongoing federal investigation.
"I don't anticipate any problems on managing the office as a result of the investigation. I think we'll be able to manage through that."
County constables primarily handle civil matters, such as serving papers in divorces and evictions.
But the Precinct 1 constables also handle a lot of inmate transportation in the downtown area.
Berry says he hasn't decided yet whether he'll seek a full, four-year term in the November election.