By Jill Serjeant LOS ANGELES, Oct 26 (Reuters) - When a wildfire burns through tens of thousands of acres of California brush, tracking a suspected arsonist sounds like a classic case of looking for the needle in the haystack. But arson investigators at work on Friday in 28,000 acres (11,000 hectares) of blackened canyon country in Southern California are using skills ranging from sifting through dirt on their knees to studying burn patterns on the tips of grass. Authorities say they are convinced that the Santiago fire in the hills of Orange County -- one of about 20 blazes to ravage the state this week -- was deliberately set and have offered a $250,000 reward for finding the arsonist. "It was not accidental by any means," Orange County Fire chief Chip Prather told reporters. "You would have to know what you are doing from a fire behavior standpoint, to take into consideration the direction of the wind blowing and the typography of the land to create a large-scale fire in a canyon like this." Heavy on manpower and with daunting environmental variables, wildfire arson investigations can be a daunting task. "It is a very difficult crime to investigate," said Rick Price, a retired arson investigator with the Los Angeles City Fire department. He said only a small percentage of California's perennial wildfires were due to arson. The first priority is determining where a wildfire started. They usually burn outward in a V- or U-shape, so the search for the sources starts at the widest part and moves backward, according to www.interfire.org, an online resource for insurers and investigators. To figure out which way the fire was moving, investigators will look for the side of a blackened tree that is most damaged, and at burned grass whose scorch patterns on the tips give clues to a fire's direction. Once at the source, the meticulous fingertip search begins for matches, flares or flammable liquid along with footprints, tire marks or cigarette ends. "Even though fire is very devastating, everything is not completely destroyed," Price said. "If you take a paper book of matches, light it and let it burn, you can still look at it and tell it was a matchbook with matches in it." Old fashioned detective work, including interviewing witnesses and first responders, can be supplemented by aerial photographs and sometimes satellite imagery. Punishments for arson in California range from fines and probation to life imprisonment in cases of extreme destruction or death. "Arsonists are not highly regarded in the prison population. They are seen as cowardly," said Timothy Huff, a retired FBI criminal profiler. "When an arsonist strikes his match, he cannot predict the ultimate consequences. This is what makes them despicable criminals."
