My question involves a security deposit in the State of: Illinois

My roommate and I had an oral agreement for one year lease till the end of June 2009. And now she wants to move out one month early, and asking me for security deposit.
She isn't on the current lease, but was on last year's lease and she paid security deposit to the landlord(management company) last year and didn't ask back when last lease ended June 2008. So I just paid my part for this year's lease.
Since she never paid me deposit, can I direct her to ask landlord for deposit even though she is not on lease. Or can I hold the deposit until someone will sublet it and pay the deposit?

Thanks.