40 ILCS 5/5-109

"Policeman": (a) An employee in the regularly constituted police department of a city appointed and sworn or designated by law as a peace officer with the title of policeman, policewoman, chief surgeon, police surgeon, police dog catcher, police kennelman, police matron, and members of the police force of the police department; and (b) An employee as defined in sub-paragraph (a) immediately above who is serving in the regularly constituted police department of a city in a rank or position which is exempt from civil service and who, immediately prior to the time he began such service, was a participant in the Policemen's Annuity and Benefit Fund Act; and (c) Any policeman of a park district transferred to the employment of a city under the "Exchange of Functions Act of 1957".