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Scientific Advances in Arson Investigations Reveal Wrongful Convictions

by Mike Rigby

Current scientific knowledge is shattering the long-held traditional beliefs of arson investigators and exposing wrongful convictions in the process. Still, old-school fire inspectors, detectives and even some judges have been slow to embrace new scientific methods and findings related to arson investigations. In Texas, such reluctance led to the execution of a man, convicted in connection with a fatal fire, who was almost certainly innocent.

Bad Science

For generations, poorly-trained arson investigators have relied on assumptions, akin to folklore, to explain how fires start and behave. But as new science confronts old cases, it has become clear that over the past few decades potentially hundreds of people have been convicted based on archaic beliefs about arson-related fires. Many of those individuals are still incarcerated, hoping that someone will come to their defense by debunking the outdated forensics evidence used to obtain their convictions. [See: PLN, Oct. 2010, p.1].

“A lot of bad science has been applied to arson investigation,” said fire expert John Lentini, who has provided testimony in over 40 arson cases since 2000. One of his recent cases involved a Massachusetts man, Victor Rosario, who was convicted of arson by Molotov cocktail even though no accelerant was found on any glass recovered at the crime scene.

Richard Roby, president and technical director of Combustion Science and Engineering, a fire protection engineering company based in Columbia, Maryland, has had similar experiences. “I shudder to think about how many wrongful convictions there are,” said Roby, who has testified for several defendants charged with arson. One, Michael Ledford, is serving a 50-year sentence for setting a fire that killed his son. According to Roby, however, Ledford could not have been present at the scene when the blaze was allegedly set. “It’s amazing to think how long it takes for basic science to be accepted,” he stated. “I lose sleep over this every week.”

And the injustice continues, as year after year, arson investigators who lack adequate training contribute to wrongful convictions. This is because the typical local investigator, whether assigned from the fire department or police force, has not had any formal academic training in fire science. Instead, they learned the trade from other arson investigators who in turn were trained by supervisors with wrong notions about fires and arson.

Better Science

At the start of his career Lentini never questioned his training. Like other fire investigators, he accepted the commonsensical but unscientific practices that were prevalent in his field. That is until his own research invalidated many of them.

For example, Lentini once believed that only intentional use of a liquid accelerant could explain the charring of a floor or walls with burn marks resembling a sharp angled “V.” Similarly, he thought that spalling of concrete, in which the surface chips after a fire, resulted from the type of high heat produced by a flammable liquid, which was an indicator of arson.

But that was prior to Lentini working on a Jacksonville, Florida case in which prosecutors charged Gerald Wayne Lewis with setting a house fire that killed his pregnant wife, his sister and his sister’s four children. The blaze showed all the conventional signs of arson, such as “pour patterns” on the floor (demarcation lines between burned and unburned areas that suggest a liquid accelerant was used). Lewis, however, maintained his innocence.

Due to the extensive publicity the case received, and because the murder charge carried a potential death sentence, the prosecution hired Lentini and John DeHaan, who had coauthored a fire investigation textbook, to evaluate other theories of how the fire may have started. One possible explanation was that one of the children, playing with matches, had ignited a sofa.

Fortunately, two doors down from the Lewis’ residence was an almost identical house. Lentini and DeHaan received funds and permission to furnish that house with the same type of furniture and carpeting as in Lewis’. Then they wired the structure with sensors, lit the sofa on fire and recorded the results. Within minutes the house was an inferno, due to a flashover. A flashover occurs when a burning object generates hot combustible gasses that ignite and engulf an entire area in flames.

To the general amazement of everyone involved, Lentini and DeHaan discovered the same burn marks on the floor of the test house that prosecutors thought indicated arson.
But rather than having resulted from a liquid accelerant, the marks were caused by flashover. Prosecutors quickly dropped the charges. “That case opened my eyes,” Lentini said. “There were all these rules of thumb you can find in the literature at the National Fire Academy that are just wrong.”

In a subsequent experiment, Lentini put to rest another arson myth: that crazing of windows – in which hundreds of fine cracks appear in the glass – occurs due to rapid heating, which again indicates the use of a flammable liquid. Lentini discovered that crazing actually results from rapid cooling. Thus, what prosecutors contended – and courts often accepted – to be a classic indicator of arson, one that has been used to send potentially innocent people to prison, was actually caused by firefighters spraying water on hot windows when extinguishing a blaze.

Nor is Lentini alone in his conclusions. The Bureau of Alcohol, Tobacco and Firearms (AFT) conducted tests in 2005 and 2007 that found burn patterns were not a conclusive way to determine how a fire started.

Fatal Injustice

Sadly, Lentini’s findings and those of other fire researchers did not prevent the state of Texas from executing a prisoner in 2004 who was most likely innocent.

In 1992, Cameron Todd Willingham was convicted of setting a house fire that killed his three young daughters. At trial, prosecutors relied on all of the typical arson indicators to prove his guilt – pour patterns of a liquid accelerant, a melted aluminum threshold, crazing of windows and burn marks on the floor – all of which Lentini and other experts later learned could be produced by flashover. And, in fact, witnesses had reported seeing flames explode out of the windows of Willingham’s house, a tell-tale sign of a flashover fire.

But science was not enough to convince Manuel Vasquez, the state’s deputy fire marshal, or the courts. Willingham was sentenced to death. His subsequent appeals were fruitless.
Then, just weeks before his execution date, a renowned fire and explosives expert from Texas, Gerald Hurst, was hired to support Willingham’s clemency petition. Hurst debunked Vasquez’s findings in a written report, calling them “invalid in light of current knowledge.” Hurst believed the fire was accidental and may have started due to a faulty space heater or electrical connection. At the very least, said Hurst, the cause of the fire should have been labeled “undetermined” as there was no evidence that it was set intentionally.

The Texas Board of Pardons and Parole was unpersuaded by Hurst’s findings and denied Willingham’s clemency petition. A copy of Hurst’s report was sent to Governor Rick Perry, but he too was not swayed, and denied a request for a reprieve.

After Willingham was executed on February 17, 2004, the Innocence Project assembled a team of top arson investigators who found that none of the arson evidence used to convict Willingham was scientifically valid. The case was such an alarming example of junk science that it was the focus of a major article in the New Yorker, a PBS documentary, investigative reporting by the Chicago Tribune and other publications, and the subject of a 2011 documentary movie, Incendiary: The Willingham Case.

The Texas Forensic Science Commission agreed to hear evidence related to Willingham’s conviction in 2006. The Commission was to hold a hearing on October 3, 2009 on a report issued by fire expert Craig Beyler, who was highly critical of the scientific methods used to convict Willingham, but Governor Perry replaced three members of the Commission two days before the hearing, which was then postponed. [See: PLN, Oct. 2010, p.40].

On April 15, 2011 the Commission issued a final report on its findings related to the convictions of Willingham and Ernest Ray Willis – the latter being a non-death penalty case involving questionable arson science in which Willis was eventually released from prison and exonerated. The report made a number of recommendations, including the adoption of national standards, more training and education for fire investigators, and standards for testimony in arson cases. The Commission, which has the motto of “Justice Through Science,” did not address whether Willingham was wrongly convicted or whether the fire officials who investigated his case were guilty of negligence or misconduct.

In May 2012, it was reported that Texas state District Court Judge Charlie Baird, who reviewed Willingham’s case, including the arson evidence and recanted testimony from Johnny Webb, a jailhouse informant, had intended to issue a posthumous exoneration – which would have been proof that an innocent man was executed, and a damning indictment of the death penalty in Texas.

Following a hearing on October 14, 2010, Judge Baird determined that “Texas wrongfully convicted” Willingham, who should be exonerated due to “overwhelming, credible and reliable evidence.”

“You can’t do anything for Willingham except clear his name,” Baird said. “When they tried Willingham, I’m convinced that everyone worked in good faith. The problem is that up until the execution, everything had changed so dramatically that you realized the science relied upon at trial was not reliable enough to take a man’s life.”

However, Judge Baird’s 18-page, undated exoneration order was never issued because the Third Court of Appeals held that he had abused his discretion by refusing to recuse himself after being accused of bias by County District Attorney R. Lowell Thompson, whose office had prosecuted Willingham. See: In re Thompson, 330 S.W.3d 411 (Tex.Ct.App. 2010).

Although Baird had voted to uphold Willingham’s conviction and death sentence when he served as an appellate judge, Thompson argued that Baird may not be impartial because he had since received an award from an anti-death penalty organization.

On October 24, 2012, Willingham’s stepmother and cousin filed a petition with the Texas Board of Pardons and Paroles, requesting a posthumous exoneration. “Since his trial, scientific advances have shattered every assumption underlying the testimony of the two fire investigators who declared to the jury and the court that Willingham set the fire that killed his children,” the petition states.

“Just because he’s dead doesn’t mean we can’t clear his name. We made a commitment to him before he died. He asked us to clear his name and maybe it will help other people,” said Eugenia Willingham, Cameron’s stepmother.

Willingham’s ex-wife, Stacy Kuykendall, who once believed he was innocent, said she opposes the petition because she is now convinced he is guilty.

At the request of the Texas Forensic Science Commission, the Innocence Project of Texas reviewed 1,025 arson-related cases to determine whether they were based on junk science such as that relied upon in Willingham’s case. According to Innocence Project chief counsel Jeff Blackburn, only a few – around “four or five” – of the arson cases may have involved bad scientific methodology. On October 5, 2012, Blackburn presented information regarding the arson case review to the Commission, which apparently has not yet taken any action.

Efforts to Help

As Willingham’s case illustrates, arson cases can be extremely difficult to overturn. With rape or murder, for example, DNA can often provide definitive proof that a suspect is innocent. But with arson this is rarely the case. That’s because although arson investigators can provide alternative theories as to how a fire may have started, they usually can’t rule out arson as a possibility. For this reason even the Innocence Project does not work on arson cases. To fill the gap, local innocence groups have organized in California, Nebraska, Indiana, Pennsylvania and several other states to investigate wrongful arson convictions.

In 2008, several faculty members at New York’s John Jay College of Criminal Justice formed a nationwide clearing-house for arson appeals and started collecting background information from prisoners around the country. Upon completion of their review, the group planned to submit the files to attorneys to introduce in court.

“We had about twenty cases that met our criteria for deficiency in science,” noted Peter Diaczuk, a forensic scientist at the college. But the organization underwriting the project, the JEHT Foundation, had invested its funds with Wall Street fraudster Bernie Madoff. In January 2009, shortly after Madoff was arrested, the foundation went broke and collapsed. [See: PLN, June 2009, p.34].

“I think we were on the brink of making an important contribution” to freeing wrongfully convicted prisoners, said Diaczuk. “Unfortunately for some of them, now it’s as if we never existed.”

Other defendants have been more fortunate. Jimmy Hebshie, 65, was indicted in May 2002 for setting fire to his store in Taunton, Massachusetts – allegedly to collect insurance money. The evidence against him included a “V” shaped burn pattern and an alert from a canine trained to detect accelerants. At his sentencing hearing in 2007, where he received 15 years, he said, “...I need to say this to you and the court: I am not guilty of this crime.”

Lentini was hired to review the case and found significant problems with the arson investigation. Hebshie’s attorney filed a motion for a new trial; a hearing was held in July 2010, and four months later the federal court vacated Hebshie’s conviction and ordered him released, criticizing the fire investigator, the canine evidence and defense counsel in a 69-page ruling. See: United States v. Hebshie, 754 F.Supp.2d 89 (D. Mass. 2010). On June 20, 2011, the U.S. Attorney’s office dismissed the indictment, effectively clearing Hebshie of the arson for which he had spent over 3 years in prison.


Despite recent advances in the forensic sciences, junk science still pervades arson investigations. In Indiana and some other states, a private investigator’s license is all that is required for someone to have the legal authority to investigate fires and testify about their origins in court. Unlike, say, someone who wants to sell real estate, who must be licensed to work in that specific field.

“It’s still the Wild West out there,” observed Justin McShane, an attorney in Harrisburg, Pennsylvania who has defended many arson cases. “You’ve still got people talking about crazed glass or using the most [fire] damage as an indicator of the source. One can only hope that in ten to twenty years we get trained scientists doing these investigations.”

However, the problem lies not only with investigators but also with judges. Even though courts are supposed to evaluate forensic evidentiary methods as a provable, measurable, peer reviewed science, many judges remain skeptical. One scientifically trained investigator, who requested anonymity, testified in 2010 at an appellate hearing for a man convicted of arson due to a pour pattern, which allegedly indicated that an accelerant had been used to set the fire.

The investigator replicated the man’s floor using the same type of rug and carpet pad, and set it alight. The test produced the same patterns without the use of a liquid accelerant.
The prisoner’s appeal was denied anyway. “I don’t want to see arsonists go free,” said the investigator, “but I certainly don’t want to see innocent people go to jail.”

Nor are defense attorneys blameless, as they often fail to challenge junk science or research advances in arson investigations. “Lawyers don’t educate themselves about the science,” noted Gretchen Bennett, executive director of the New England Innocence Project.

Scientific advances have never been quick to catch on. Consider Galileo, who was imprisoned for his then-heretical belief that the Earth revolved around the Sun. But that was before the dawn of empirical science, which bases assumptions – or hypotheses – on observable, testable data.

Today, there is no excuse for shunning such scientific methods. Yet while DNA evidence has been widely embraced, modern arson science is slow to be accepted in courthouses across the nation. In fact, an argument can be made that the medieval church was in some ways more accepting than we are today: at least Galileo was allowed to live despite his scientific beliefs. Willingham was not so fortunate, despite scientific evidence that weighed heavily in favor of his innocence.

Sources: Discover Magazine, Huffington Post, Austin American-Statesman, Taunton Gazette,, The Lowell Sun,

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