My question involves landlord-tenant law in the State of: Massachusetts

I moved to a new apartment in September, and gave the check for my security deposit to my roommate to secure the rental. I am moving out as early as May 1st (holding onto the occupancy in my current apartment for the month for the purposes of giving my landlord proper notice to quit), and as late as June 1st. Back in the fall, I asked my roommate if the landlord had given a reciept for my security deposit, and her reply was that the landlord didn't have it, she had used my check to pay back the security deposit of the tenant I was replacing. I spoke to the superintendent, and then the landlord of the building about my lack of concern over the lack of a paper trail, etc (The deposit WAS given via check, and had "security deposit" clearly noted on it). They assured me that they were holding A security deposit for the unit, and that I wouldn't get "screwed over". There is no lease or written agreement of any kind.

My question is this: As far as who would be held liable for not putting my deposit in an interest bearing account not in the landlord's name, etc, it would be my roommate who recieved the deposit, right? Unless she can somehow prove otherwise, is my landlord liable for this in any way, shape, or form?