MIJ,
The myths of fire investigation are alive and well. Here is the mantra of what I call the "professional amateur: "NFPA 921 is only a guide, not a standard."
By the way, may we know your real name?
Pat
Pat Kennedy, CFEI, CFPS, MIFireE
Fire and Explosion Analyst
Sarasota, Florida
[
www.kennedy-fire.com]