It can be difficult for investigators (in both large career departments and small volunteer organizations!) to get good information and training relating to fire investigation. 

You'll find great resources at:

Interfire VR http://www.interfire.org/

USFA http://www.usfa.fema.gov/nfa/coffee-break/investigation_index.shtm

NETC Library http://www.usfa.fema.gov/data/library/research/topics/top_fire_investigations.html and pathfinder (archived page from 2013)  https://web.archive.org/web/20130808192222/http://www.lrc.fema.gov/path_arson.html 

Certified Fire Investigator Trainer http://www.cfitrainer.net/

IAAI Chapter 23 (New York State) http://www.nyfireinvestigators.com/link/index

SOS Fires: Youth Intervention Programs http://www.sosfires.com/ 

Here's our Library's resource list, prepared for the Academy's Fire/Arson Investigation class but useful as a stand-alone:

Fire-Arson Bibliography Sept 2016.pdf 

...and our guide to resources on juvenile firesetting:

JuvenileFiresetterBib.pdf