Are arson investigations an art or science?

Until 1992, some arson experts say, guidelines for determining arson were largely based on hand-me-down myths practiced by fire investigators with little formal training. In 1992, the National Fire Protection Association released its first arson guidebook based on years of studies and simulations.

The guidelines, known as NFPA 921, were initially met with resistance from fire marshals and officers across the country, who believed arson investigations were an art rather than a science.

"It was gumshoe work, not really analysis and conducting studies," said Gerald Hurst, an arson investigator with a Ph.D. in chemistry, who examined the arson findings in the Cameron Todd Willingham investigation from 1991. He concluded the arson science used in his case was "junk."

So how do lawyers prove a man's innocence more than two decades after a fire occurred?

The task is almost impossible, said David L. Faigman, a law professor at the University of California, San Francisco. Disproving an arson case is more challenging because the findings aren't as clear-cut as DNA, he said. He said the petitioners have the burden to prove the arson didn't occur and that they weren't involved.

Link:
http://www.cnn.com/2010/CRIME/08/12/pennsylvania.arson.dougherty.case/index.html?hpt=C1