Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Excellent information for the investigator

This book was well written, and detatiled. The lessions were followed buy examples that illistrated the key points. I am now prepareing to go into narcotic's, and the authur has vast knowledge in the subjct of narcotic's. This was an execllent begining to the use of informants. The authur has clearly set up the paramitors for the selection, preparation, and use of informants. The cases that are talked about in the book are from taken from current and historical cases, both narcotics and other crimes. I found this book very interesting. I have loaned it out to a fellow Officer who has commented that it is an excellent book and he has been in narcotics for 7 years.