Advances in forensic fire science helps overturn arson convictions.

 Almost three decades ago, David Lee Gavitt was convicted of starting the fire that killed his wife and two children. He was sentenced to life in prison.

This week, Gavitt, now 54, was set free based on new scientific evidence proving that the fire was accidental.

Gavitt’s is the most recent case that highlights a shift in thinking about what causes a fire — and how what once seemed like telltale signs of arson can actually be the opposite. Last week, a Chicago-area man was released after prosecutors dismissed arson-murder charges against him stemming from a 1984 fire. And Ernest Ray Willis of Texas was exonerated in 2004 after spending almost 20 years on death row, based in part on evidence presented by renown fire scientist Gerald Hurst.

Gavitt’s case involves both a crucial error in forensic science and the debunking of myths that have been part of arson investigation for decades: A lab erroneously concluded that a carpet sample contained evidence of gasoline, and investigators assumed that a fire that burned quickly as the one in the Gavitt household must have been intentionally set. We now know that because of a scientific phenomena called “flashover,” a fire can burn hot and fast without being set on purpose — and can leave patterns on a surface that can be mistaken as pour patterns.

“In light of modern fire science, there is simply not one shred of credible evidence that the fire at the Gavitt residence was intentionally set,” wrote John Lentini, an expert in fire science, in an affidavit presented to a judge last fall by the Innocence Clinic at the University of Michigan Law School, who worked extensively on Gavitt’s case.

Lentini and Hearst are two of the key scientists who helped change the long-held assumptions about how fires burn by starting and studying their own. “The fire investigation community largely consists of people who are firemen. They’re not scientists. They don’t have any formal scientific training,” Lentini told FRONTLINE. “Extinguishing a fire and investigating a fire involve two different skill sets and two different mindsets.”
http://www.pbs.org/wgbh/pages/frontline/criminal-justice/death-by-fire/new-fire-science-helps-overturn-michigan-mans-murder-conviction/