If you’re a crime, mystery or thriller writer with no legal background, a few good writing books can mean the difference between convincing your audience you know what you're talking about and coming off as amateurish. Not to mention, these books are also good for ideas, especially if you need to murder a character.

Howdunit: How Crimes Are Committed and Solved 

Includes the best of the Howdunit crime series as well as 13 new chapters on key topics such as street gangs, the drug trade, terrorism, and forensics.

This is one of my favorite. I use it regularly when I’m working on the AVIA series. It shows such wonderful things as how an autopsy is performed, information on serieal killers an con artists and how to process a crime scene.

Police Procedure & Investigation: A Guide for Writers (Howdunit) 1st Edition

If you can't guess, I'm a real big fan of the Howdunit series.  This book is just as useful if not more useful than the above Howdunit Overview with the most popular pieces of information. This book gives you information on street cops, the American criminal justice system, various types of murders, body handling and autopsies, con artists, interrogations, sex crimes, sexual predators and drug enforcement, as well as a lot more.

HowDunit - The Book of Poisons First Edition

You just can't go wrong with a comprehensive book of poisons. 

Discover Deadly Doses to Kill Off Characters

The readers of your crime and mystery stories should be trying to figure out "whodunit"—not wondering why your facts don't make sense. If you want to kill off characters with something poisonous, you need to know how a villain would gain access to such a poison, how it would be administered, and what the effects on the victim would be. Book of Poisons can help you figure out all of the details of proper poisoning.

This thorough guide catalogs the classic poisons, household poisons, poisonous animals and plants, poisons used in wars, and more. With information on toxicity, reaction time, effects and symptoms, and antidotes and treatments, you'll know exactly what your villain needs to succeed and exactly what could foil his plans. You'll also find:

• information about how real toxicologists uncover poisoning crimes
• a history of famous poisoners
• advice on how you can create your own fictional poison
• case histories that give examples of when the poisons listed were used in literature, movies, and real life

With alphabetical organization and appendices that cross-reference by symptoms, form, administration, and other methods, you'll be able to find the perfect poisons to fit your plot. Plus, a glossary of medical terms makes decoding symptoms and treatments easy for the writer with no medical background.

Book of Poisons is the comprehensive reference you need to create deaths by poison without stopping readers dead in their tracks over misguided facts.

Forensics: A Guide for Writers (Howdunit) Kindle Edition

If you are intrigued by shows like Forensic Files, this book will give you the nitty-gritty about forensics in solving crimes so that you can use the information in your writing in order to make it more realistic.

If you are a crime writer, mystery writer, thriller writer who focuses on crimes or have any type of fiction manuscript that involves a crime, I can't say enough about these books.  They've really helped me make the crime scenes more realistics and helped me with criminal character development.