40 ILCS 5/19-112
Any person who is certified and appointed to a position as an employee of the house of correction, as employee is defined in this Division, who has served as an employee of the house of correction by virtue of temporary appointment prior to such certification and appointment, shall have the right to have credited to such employee for pension and widow's pension purposes the period of time such employee served in such position by virtue of temporary appointment, upon such employee paying into the house of correction employees' pension fund such amount of money as he would have paid into such pension fund had he been a member of such pension fund during such period of temporary employment, together with interest at the rate of 4% per annum upon each such payment from the time such payment would have been made had he been a participant in the fund, until such payment is made; provided, however, such right to receive credit must be exercised by such employee on or before July 1, 1952, or within 3 years after the date of his appointment and certification, whichever is the later date.
40 ILCS 5/19-112