EAST STROUDSBURG, Pa. -- The clues were everywhere. A young woman lay dead in a burned cabin at a church camp, while her father survived.
Most of the lessons taught to budding fire investigators stood out at the scene. Several specialists -- the county fire marshal, a state-hired fire analyst, a chemist -- spoke without hesitation that it all proved arson -- and murder.
No one questioned that conclusion. It was a textbook case, and the father, Han Tak Lee, 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 widely accepted beliefs about how fires work and the telltale trail they leave .
Today, fire investigators are taught that the clues relied upon in the 1989 investigation of the cabin fire don't prove anything more than an accident.
And some of the leading US specialists on arson say that Lee was the victim of a horrible tragedy, not a criminal. There could be hundreds more wrongfully convicted of arson, they say.
Pennsylvania courts have repeatedly rejected the argument that the prosecution's case was built on bad science. Lee was convicted of murder in 1990 and several appeals in Pennsylvania courts have won him no relief. He is now seeking a hearing before the state Supreme Court.
"I never killed my daughter. I never set the fire. I'm not the right person to be here," Lee, 71, says through a translator at Rockview medium-security prison in Pennsylvania.
Leading fire investigators across the country estimate that there could be hundreds of mistaken arson prosecutions, all built on the same ideas that were uprooted more than a decade ago.
The new arson science could become the most powerful tool to reveal wrongful convictions since DNA testing began overturning rape and murder cases in 1989. Critics also say it is still happening, because some investigators continue to prosecute cases based on discredited methods.
"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 on arson that helped bring the 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 Lees were in Pennsylvania that morning 17 years ago because Han Tak Lee and his wife had hoped to heal their oldest daughter's mental problems.
The family's Pentecostal pastor suggested the church retreat. Father, daughter, and preacher prayed until the wee hours of the morning. Then, the fire -- one that, to investigators, pointed clearly to Lee. Part of the reason is 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."
Firefighters and 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. And it can cause a fire to burn down.
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.
It wasn't until 1992 that a guide by the National Fire Protection Association clearly laid out 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.