The NFPA methodology document that fire and explosion investigators are expected to work to, in its 2021 edition.

NFPA 921 walks through origin and cause investigation as a scientific process: hypothesis, testing, and eliminating alternatives. This edition rebuilds Chapter 6 so fire pattern analysis and arc mapping form one origin-determination process, and folds the old Chapter 20 into Chapter 19. Used by fire investigators, forensic engineers, claims investigators and attorneys. NFPA paperback, ISBN 9781455926466.