Just call the cops. you CAN'T get in trouble for doing that.
Besides, talking to her yourself is probably what she wants you to do, to draw you into her drama. The cops will get the story, and probably be back 20 or 79 times before "the shit happens" but at least they will have a record of it.
Then you can go on TV as the "neighbor" to say, they were such a lovely couple, I don't know what could have happened that she ended up with her head in a pillow case.... Better her's kevv, than yours.....