Janice L. Bledsoe, a private defense attorney who joined State's Attorney Gregg Bernstein's administration last year to prosecute police misconduct cases, is no longer with the office.
Cheshire said the office had "launched a search to find a replacement" and did not provide additional details.
Bledsoe could not be reached for comment. She joined the office last May.
As the police integrity prosecutor, Bledsoe was handling several high-profile investigations, including bringing charges against homicide Det. Anthony Fata, who prosecutors accuse of lying about shooting himself in a downtown parking garage.
She was also leading the unresolved investigations into Officer