Philadelphia fire investigators had no scientific basis to conclude that a 1985 rowhouse fire in Oxford Circle was arson, a defense expert testified about the blaze that killed two boys and sent their father to death row for their murder.
Nationally known fire consultant John Lentini said that when he heard that a city fire marshal, and then a second, had identified three separate points of origin for the fire, "I said, 'He must be magic, because it can't be done.' "
The fire, he said Tuesday in Common Pleas Court, could have started from a smoldering cigarette.
Lentini, head of Scientific Fire Analysis L.L.C. in Florida, testified on behalf of Daniel Dougherty, who has been imprisoned for 16 years after being convicted in 2000 of burning the home.
Dougherty insists that he's innocent in the deaths of 3-year-old John and 4-year-old Daniel Jr., and that he's a victim of now-discredited ideas about how fires act, grow, and travel.
The prosecution in Dougherty's court-ordered retrial has relied on the 1985 findings of Assistant Fire Marshal John Quinn, and on this week's support of those findings by consultant and former fire marshal Thomas Schneiders.
Lentini, who has helped write national standards and texts for fire investigation, said they got it wrong. Since the 1990s, investigators have been lighting test fires - such as could be started by a dropped cigarette - that duplicate the type of damage and burn patterns found in the Carver Street home, he said.
Quinn, who is too ill to testify, and Schneiders, who reviewed the case file, said the fire was set in three places - a sofa, a love seat, and under a dining-room table.
Lentini showed drawings and videos depicting a fire condition called full-room involvement - in which a room becomes an inferno - and said it could create the burn patterns that Quinn mistook for arson.
The prosecution says Dougherty set the fire to get revenge on two women - his girlfriend, Kathleen Schuler, who owned the home; and the mother of the boys, Kathleen Dippel, from whom he was separated. In anger over their rejections, he destroyed the house of one and the children of the other, prosecutors said.
The defense contends that the cause of the fire could not be determined and that Quinn failed to recognize advancements in fire science and arson-detection in the 15 years between the blaze and Dougherty's first trial.
Dougherty, Schuler, and other friends and visitors to the home were smokers. Dougherty said from the start that he awoke on the couch to see the curtains on fire, ran outside, then tried desperately to rescue his boys.
His death sentence was vacated in 2012, becoming a life sentence.
Lentini testified about the twin phenomena of flashover and full-room involvement, and how the latter can quickly cause so much destruction that it's impossible to determine where or how a fire began.
That's what happened in this case, he said. The cause should have been listed as "undetermined."
That Quinn thought he could identify not just one but three separate points of origin within the ruins, Lentini said, showed "a very poor understanding of what's possible in fire investigation."
A Tucson test fire, set in a trailer home in 1992, showed that the lowest and deepest charring - long considered the starting point of a fire - actually occurred well away from the initial source. Additional tests showed the same.
"This," Lentini said, "has shaken the fire-investigation community to its bones."
Lentini said he has worked on or knows of 50 cases in which people have been wrongly accused or imprisoned based on flawed fire investigations.
Around the country, inmates have challenged convictions they say are based on old, disproved science.
The prosecution rested its case Tuesday, its witnesses having included Schuler and Dippel, who described Dougherty as a mean drunk who hit them if they objected to his drinking.
Jurors were shown photo after photo of the charred interior of the home. They were shown a single black-and-white photo of the boys, lying where they were found in the same second-floor bed.
No one testified, in 2000 or at the current retrial, that they saw Dougherty strike a match or flick a lighter. No one said he disliked his children or talked about setting a fire.
Dougherty's original trial attorney failed to challenge Quinn on the science, which ultimately led an appellate court to grant a retrial.
For most of the trial, Dougherty has kept his head low, taking notes as witnesses spoke. On Tuesday, as he was led from the courtroom during a recess, he turned to his relatives among the spectators and gave a thumbs-up.