Retirements in the Chicago Police Department outpaced hiring by 975 officers last year.
The Chicago Sun-Times found that the city spent a record $116.1 million on overtime in 2015 to make up for a shortage in manpower.
That number is up 17.2 percent from the previous year when $99 million was spent on overtime.
Records show that 2,575 Chicago Police officers have retired since Mayor Rahm Emanuel took office in May 2011. Last year, 457 officers retired from the force with 120 more leaving during the first three months of this year.
Records show that the second-highest monthly spending on police overtime -- $10.4 million -- occurred in November when a judge ordered the city to release a video showing an officer fatally shoot Laquan McDonald.
Protesters took to the streets to demand the resignations of Cook County State's Attorney Anita Alvarez, Mayor Rahm Emanuel and then-Police Superintendent Garry McCarthy as Officer Jason Van Dyke was charged with first-degree murder.
Officers were deployed on overtime to try to keep the protests peaceful.
Chicago FOP President Dean Angelo has labeled mounting overtime unhealthy, unsustainable and a recipe for officer burnout.
