Landlords in Chicago are required to "maintain windows, exterior doors or basement hatchways in sound condition and repair and substantially tight and to provide locks or security devices as required by the municipal code, including deadlatch locks, deadbolt locks, sash or ventilation locks, and front door windows or peepholes;" (CRLTO 5-12-110).
I recommend consulting an attorney to discuss this issue in more detail, specifically whether or not the locks and security you have currently comply with the City of Chicago Building Code. If they do not comply, you may be able to make the repairs and deduct them from your rent.
However, if you are going to repair and deduct, I highly recommend having an attorney help you with the formal procedure so it complies with the CRLTO and you don't run into problems for not paying rent.
This answer is intended as informational only, and does not constitute legal advice or form an attorney-client relationship between us.
My colleague is correct. I'll add that depending on your state's laws, a landlord might have a duty to ensure the safety of his tenants if there's a propensity for criminal activity in the area.
DISCLAIMER: Brandy A. Peeples is licensed to practice law in the State of Maryland. This answer is being provided for informational purposes only and the laws of your jurisdiction may differ. This answer based on general legal principles and is not intended for the purpose of providing specific legal advice or opinions. Under no circumstances does this answer constitute the establishment of an attorney-client relationship. For legal advice relating to your specific situation, I strongly urge you to consult with an attorney in your area. NO COMMUNICATIONS WITH ME ARE TO BE CONSTRUED AS ARISING FROM AN ATTORNEY-CLIENT RELATIONSHIP AND NO ATTORNEY-CLIENT RELATIONSHIP WILL BE ESTABLISHED WITH ME UNLESS I HAVE EXPRESSLY AGREED TO UNDERTAKE YOUR REPRESENTATION, WHICH INCLUDES THE EXECUTION OF A WRITTEN AGREEMENT OF RETAINER.