740 ILCS 105/4
The plaintiff at any time before, but not later than 10 days after, the filing of the answer, unless further time be granted by the court, may file interrogatories in writing concerning matters material to the allegations of the complaint or respecting the ownership of the property upon which it is claimed the nuisance is maintained. A full answer to each interrogatory under the oath of the defendant shall be filed with the clerk within 10 days after a copy of the interrogatories has been served upon him or her or his or her attorney-at-law. For a failure to so answer interrogatories the court may strike the answer to the complaint from the files and enter an order of default and final judgment, and a rule to answer interrogatories may be entered and the court may punish a defendant for contempt of court for a refusal to obey such rule. No person shall be excused from answering interrogatories under oath on the ground that an answer may tend to incriminate him or her or subject him or her to a penalty or forfeiture. The answer may be used as evidence against, but not for, the defendant; it shall not be used against the defendant in any criminal proceeding nor shall he or she be prosecuted or subjected to a penalty or forfeiture for or on account of any transaction, matter or thing disclosed by him or her in such answer responsive to the interrogatories.
740 ILCS 105/4