Double Jeapordy

Amanda Knox is waiting to hear verdict of her murder case for the third time.  She was found guilty at her first trial, and to put it simplistically it was overturned.  On the second trial, she was found not guilty.  In our system, the fight would be over.  She was acquitted.  The prosecutors could not pursue the case again because jeopardy would attach and her case would be over.  However, in the italian system, the verdict, regardless of what it may be, can be appealed.  When does it become a vendetta?  When does it ever stop?  I guess the theory is lets try every possible theory of a case until something sticks.  I don't know if she is guilty or innocent.  I was not there.  However, it does appear there is a lack of evidence and a tainted crime scene.  It is time to let go.