25 ILCS 5/9
The manner of effecting imprisonment of any person by either house for disorderly or contemptuous behavior in its presence, shall be by a warrant, under the signature of the presiding officer for the time being of the house ordering the imprisonment, countersigned by the acting secretary or clerk, running in the name of the People of the State of Illinois, and may be directed to the sergeant-at-arms or doorkeeper of the house, or to the sheriff of the county in which the General Assembly is convened, commanding him or her to commit the prisoner to the county jail, and deliver the prisoner to the keeper thereof, and the jailer to receive the prisoner into his or her custody and safely keep the prisoner for the time for which the prisoner is committed, or until the prisoner is duly discharged.
25 ILCS 5/9