New fire science could overturn arson convictions across the nation

The clues were everywhere. A young woman lay dead in a burned cabin at a church camp in East Stroudsburg, Pennsylvania, while her father survived.

Most of the lessons taught to budding fire investigators stood out at the scene. The local experts spoke without hesitation that it all proved arson and murder. No one questioned their conclusion. It was a textbook case, and the father, Han Tak Lee, a South Korean immigrant, was dealt a guilty verdict and a life sentence.

Except the textbooks were wrong. Within a few years of Lee’s conviction, scientific studies smashed decades of earlier, widely accepted beliefs about how fires work and the telltale trail they leave behind. Today, fire investigators are taught that the clues relied upon in the 1989 investigation of the cabin fire do not prove anything more than an accident.

Some of the leading U.S. experts on arson say that Lee was the victim of a horrible tragedy, not a criminal. There could be hundreds more wrongfully convicted of arson, such experts say.

A definitive count is not possible, but leading fire investigators across the country estimate that there could be hundreds of mistaken arson prosecutions.

“How do you know someone’s guilty if you don’t know a crime has been committed?” says Richard Custer, a principal architect of a pivotal document that helped bring changes to light.

Another widely known investigator, John J. Lentini, has been a consultant on Lee’s case, analyzing evidence and testimony. His conclusion: “While the Commonwealth’s witnesses may have believed that they were testifying truthfully, the fact is that the jury was misled by objectively false testimony.”

The reasons investigators said the fire pointed to Lee came from what they were taught about arson in those days:

• Fires always burn up, not down.

• Fires that burn very fast are fueled by accelerants; “normal” fires burn slowly.

• Arsons fueled by accelerants burn hotter than “normal” fires.

• The clues to arson are clear. Burn holes on the floor indicate multiple points of origin. Finely cracked glass (called “crazed glass”) proves a hotter-than-normal fire. So does the collapse of the springs in bedding or furniture, and the appearance of large blisters on charred wood, known as “alligatoring.”

Investigators arrived at these conclusions through decades of observation. But those beliefs had never been given close scientific scrutiny, until the 1970s and 1980s. Once researchers began to apply the scientific method to beliefs about fire, they fell apart. A major revelation came from greater understanding of a phenomenon known as “flashover.” When a fire burns inside a structure, it sends heat and gases to the ceiling until it reaches a certain temperature — and then in a critical transition, everything combustible in that space will catch fire. Instead of a fire in a room, now there is a room on fire.

When that happens, it can leave any number of signs that investigators earlier thought meant arson — like the burn holes on the floor that used to prove multiple starting points. And it can cause a fire to burn down from the ceiling — not up.

Significantly, flashover can create very hot and very fast-moving fires. And it can occur within just a few minutes, dashing the concept that only arson fires fueled by accelerants can quickly rage out of control.

The studies began to chip away at the old beliefs, but it took years. Through the 1980s, texts at the National Fire Academy in Emmitsburg, Maryland, still taught the traditional techniques. It was not until 1992 that a guide by the National Fire Protection Association — “NFPA921: Guide for Fire and Explosion Investigations” — clearly laid out, in a document relied upon by authorities nationwide, that the earlier beliefs were wrong.

“It’s not that they’re bad investigators or there’s been any conspiracy to promulgate erroneous conclusions — it’s just the way it was,” says Custer, the former associate director of the national Fire Research Laboratory and one of the principal editors of the 1992 guide. “How many years did we think the Earth was flat?”

How many could be wrongfully convicted of arson? There are 500,000 structure fires overall a year; 75,000 of them are labeled suspicious. Lentini says most experts believe the accuracy at best 80 percent — meaning as many as 15,000 mistaken investigations each year, and who knows how many convictions.