Don't quite understand how access was done through the window without the police seeing it as a "forced" entry, especially if the screen was cut. Doesn't make sense unless the entire window was popped out of the frame.
Sorry your your troubles.
To clean the toilet and and such, you can run water through a garden hose (even if there is snow on the ground) as long as the water does not sit. You can clean up the mess, and then drain your holding tanks immediately. Unless you are in minus 100 degree weather, you should be able to clean it up, rinse it down, and flush it out before any freezing takes place. Just don't let the water sit giving it any chance to freeze. Drain all your sewer lines when done too.