Legal Question in Landlord & Tenant Law in Illinois

Insufficient information, however.....If you are the tenant and this man has lived with you, it SOUNDS like he is your subtenant unless the landlord has specifically agreed that he is a co-tenant with you (this can occur if the landlord accepts rent directly from him). Either way, Illinois state law requires a VERY specific form of notice served in a VERY specific way, to evict someone, and without seeing the "letter" it is hard to say BUT if it is in proper form and he is a co-tenant and it was sent certified mail/return receipt requested (as required by law), it COULD be valid notice. HOWEVER, if you and the man make it difficult for your landlord (including forcing the landlord to go through the required legal steps to evict only him), the landlord's next step could be to evict all of you. Time to talk to your landlord before things get out of hand.