720 ILCS 5/31-4: Obstructing justice.

(a) A person obstructs justice when, with intent to prevent the apprehension or obstruct the prosecution or defense of any person, he or she knowingly commits any of the following acts:

(1) Destroys, alters, conceals or disguises physical evidence, plants false evidence, furnishes false information; or

(2) Induces a witness having knowledge material to the subject at issue to leave the State or conceal himself or herself; or

(3) Possessing knowledge material to the subject at issue, he or she leaves the State or conceals himself; or

(4) If a parent, legal guardian, or caretaker of a child under 13 years of age reports materially false information to a law enforcement agency, medical examiner, coroner, State's Attorney, or other governmental agency during an investigation of the disappearance or death of a child under circumstances described in subsection (a) or (b) of Section 10-10 of this Code.

(b) Sentence.

(1) Obstructing justice is a Class 4 felony, except as provided in paragraph (2) of this subsection (b).

(2) Obstructing justice in furtherance of streetgang related or gang-related activity, as defined in Section 10 of the Illinois Streetgang Terrorism Omnibus Prevention Act, is a Class 3 felony.