Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Portrait of a Killer

Not only was this a well researched and written book,I belive it to be the most convicing book on who Jack the Ripper was.I spent most of my life in Law Enforcement. In an Crimnal Investigator capacity. I have read almost all of the books on this Subject. The evidence is really quite convencing, for this old of a crime.I belive that the author,has her man. When there is this much evidence,you just cannot walk away with a reasonable doubt. At any rate, a person who have to read almost all the books on the Ripper's case. To see what I mean.Mrs. Cornwell done a supreme job! I too would take it into court. I belive a Judge would convict. I never try to guess a Jury.