Authorities did not say whether they believed the corrections officer, whose name was not released, would face charges or if the officer was believed to have assisted in the breakout.
Separately, Major Charles Guess of the New York State Police told reporters on Friday that investigators had spent "countless hours" interviewing another prison worker, Joyce Mitchell, who is accused of assisting in the breakout.
Mitchell, 51, a training supervisor in the prison tailor shop who is charged with giving hacksaw blades to the convicted murderers, lost her nerve to drive their getaway car and instead checked into a hospital with a panic attack, authorities said.
The two inmates went through prison cell walls, a steam pipe and a manhole cover to escape, officials said.