Can you be more specific about the murky situation we're talking about here? I moved offices from Oak Park back into Chicago a few months back. The landlord never collected the key. My old office was rented out (I can see from the window). Can I go look around inside it?
It's not that you have the right to go back. Rather, by failing to change the locks they might have some liability if you did go back.
If a lessor or landlord in Illinois does not change or rekey the unit's lock before the day the new tenant or lessee takes possession, and a THEFT occurs at that dwelling unit that is attributable to the lessor's failure to change or rekey the lock, the landlord is liable for any damages from the theft that occurs as a result of the lessor's failure to comply with the lawhttp://www.securitydepositlaw.com/blog/chicago-tenants-right...
No, that's actually not true of commercial leases in Chicago. It's true of residential leases because residential landlords have a whole bunch of very specific issues about key changes.
But stipulate that it was true. What bearing does that have on this case? If I go into that office and steal $5000 worth of computer equipment, am I not liable for felony grand theft because the landlord has civil liability to the tenant?
Liability can be shared and a tenant may greatly prefer going after an ex. landlord vs. some random person.
Granted, this does not apply in your case, but Chicago does have mixed use Residential/Commercial leases which is covered.
Now suppose a tenant goes back to retrieve their property the day after there lease ends. Which under some situations they are allowed to do. Key works, the enter building...
IANAL, but would suggest this is a situation the owner would like to avoid.
A failure to change the locks does not mean you have created an attractive nuisance to former employees.