Evidence Under Attack in Two Texas Arson Convictions

May 4, 2010 — -- Arson charges can be difficult to rebut. But getting a conviction overturned can seem almost impossible -- even when the stakes are a matter of life and death.

Todd Willingham may be a prime example. In 1992 he was convicted and sentenced to death for killing his three children in an arson fire in Corsicana, Texas.

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While Willingham awaited his execution day, virtually every piece of physical evidence against him was reviewed and pronounced inadequate by independent fire expert Gerald Hurst. Hurst has spent years arguing that hard science needs to be brought into fire investigations.

"They said they found 20 indicators of arson. There were zero indicators of arson," said Hurst. "The Willingham case is like a hundred other cases I've seen, except that they executed him. The others are rotting away in prison."

Last year a scathing report by Dr. Craig Beyler for the Texas Forensic Science Commission concluded the Willingham arson investigation was "nothing more than a collection of personal beliefs that have nothing to do with science-based fire investigation."

Nevertheless, one of the original fire investigators in the case, Doug Fogg, remained adamant.

"I have no doubt the fire was deliberately set," he told ABC News.

Among the evidence Fogg used to support his conclusion was something called "crazed glass" -- tiny cracks in glass that sometimes show up in the aftermath of a fire.

Arson expert John Lentini described the phenomenon.

"This used to be evidence of arson," said Lentini. "It was a myth. They used it on Todd Willingham. They said we know this fire was a rapid fire 'cause we've got this crazed glass."

Turns out such glass breakage has nothing to do with an intentionally-set fire, even one in which an accelerant such as gasoline was used heavily.

"You cannot make crazed glass by heating it rapidly," said Lentini, "but you can by cooling it rapidly" -- as often happens, he said, because of the spray of firefighters' hoses.