My question involves roommates in the State of: Massachusetts

Sadly, unpaid bills is more of a minor thing in this situation - I've arranged for my landlord to come over to my apartment to mediate things as a last resort before I inevitably take them to small claims court over a fair sum of unpaid bills, but here's my big concern -

The roommate relationship went downhill at the time I started asking my roommates (they're a couple, whom I was dumb enough at the time to expect would be trustworthy) to pay equal shares of the bills. That's about when the thefts started. It began with minor things, like toilet paper out of grocery bags in my room, but since then, they have collectively stolen/thrown out over $200 worth of my possessions, including video games, my spare computer monitor, my best friend's book, an xbox 360 controller, and about $50-60 worth of spices I use for cooking when my friends come over. Pretty much any possession of mine that's not nailed down. Most of my stuff is in my bedroom behind a padlock, but I literally cannot keep anything outside of my bedroom. Additionally, my mail has suddenly stopped making it to the apartment - bills (even worse, because they refuse to pay utilities without a hard copy of them, and I don't have a printer), my netflix movies, but things for my roommates seem to keep arriving.

I know it's a civil issue, and all he said, she said, especially with the things I can't verify the locations of, but is there anything I can pursue? The monitor, book, and controller are in their room, I can see them, and I have asked for them back, which they conveniently ignore the requests for, and it's kind of frustrating to see them getting away with all this.

Is there anything I can do?