oh my gosh, that is the most horrible thing to ever happen! I feel so sorry for your loss!
I think you should sue them, because, if they saw the dog jump into your yard, they should have gotten it out. And second, if they knew you had dogs, and the dog that killed minnie was vicious, that is known as a "doggy murder", which is illegal underneath the ASPCA sercomstances! You SHOULD SUE them!!!
Rest in peace- Minnie, she was a wonderful dog 