(720 ILCS 5/7-9) (from Ch. 38, par. 7-9)
    Sec. 7-9. Use of force to prevent escape.
    (a) A peace officer or other person who has an arrested person in his custody is justified in the use of such force to prevent the escape of the arrested person from custody as he would be justified in using if he were arresting such person.
    (b) A guard or other peace officer is justified in the use of force, including force likely to cause death or great bodily harm, which he reasonably believes to be necessary to prevent the escape from a penal institution of a person whom the officer reasonably believes to be lawfully detained in such institution under sentence for an offense or awaiting trial or commitment for an offense.
(Source: Laws 1961, p. 1983.)