I found an interesting video from 1990 giving a bit of interesting insight into how fire departments, LE, and other agencies handle crash investigations. The video is shot on scene at a real crash of a Cessna Citation.
http://www.firerescue1.com/search-rescue/videos/529404-airplane-crash-essential-operations/
Crash Report: http://aviation-safety.net/database/record.php?id=19900924-0