A conviction up in smoke?

The evidence seemed overwhelming.

Investigators determined a house fire that killed a woman and two children had been deliberately set. A witness said she had seen George Souliotes, who owned the house and was evicting the tenants, at the scene minutes before flames erupted.

Forensic investigators even matched a flammable substance on Souliotes’ shoes to fire debris from the Modesto house.

Thirteen years later, the evidence that convicted the Greek immigrant of triple murder and sent him to prison for life without parole is beginning to unravel.

Although prosecutors say they remain certain that Souliotes set the fire, scientists said investigators concluded the blaze was arson based on assumptions that are now known to be false.

For decades, fire investigators believed accelerant-propelled arsons left signs: melted steel, glass etched by tiny cracks, certain patterns and markings.

But when the theories were finally tested, scientists learned the conditions also were found in accidental blazes.

The turning point for fire science came in 1992 with the publication of a seminal guide by the National Fire Protection Assn.

The report dispelled myths that had guided fire investigations for decades, but years passed before the report’s conclusions were embraced.

Even today there are investigators with little training who cling to the old beliefs, according to leading fire experts.

“There is still a pretty sizable rear guard who don’t want to admit they were doing it wrong,” said John Lentini, a fire scientist who was hired by Souliotes’ defense. “It is understandable, because the worst thing you can do is send a person to prison for a crime they did not commit.”

The execution of Todd Willingham in Texas in 2004 for the arson murders of his three children haunts many fire experts. Subsequent reviews of the forensic evidence indicated that blaze was probably accidental.

Investigators are so concerned that bad science may have wrongly convicted innocent people that several have agreed to review old cases where the science was wrong and there was little other evidence.

“There is a real sense of insecurity among a lot of people in the field that the Willingham case may represent the tip of the iceberg,” said James Doyle, director of the Center for Modern Forensic Practice at New York’s John Jay College of Criminal Justice, which is screening the cases.

“You can’t help but be nervous given how different the fire science is today from the folklore” that guided probes in the past, he said.

Souliotes’ case might have been forgotten if not for his sister, Aleka Pantazis, 63, a Glendale resident whose efforts helped debunk what a prosecutor had called “the most conclusive scientific evidence” of his guilt.

Fire scientists say that arson investigators misinterpreted the evidence at the scene, and a former FBI agent hired by Pantazis found Souliotes was truthful during a polygraph test when he denied setting the blaze.

“She has fought like a lion,” Souliotes, 69, said during an interview at Salinas Valley State Prison near Soledad.

The woman’s campaign -- aided by friends from St. Sophia’s Greek Orthodox Cathedral in Los Angeles -- is now in the hands of the U.S. 9th Circuit Court of Appeals, which will soon decide whether Souliotes should have his case reexamined. He argues that he is innocent and received incompetent legal representation.

Pantazis, whose thick accent and blue eyes match her brother’s, has raised money, tracked witnesses, made timelines and reenacted events to try to prove her brother did not set the 1997 fire that killed Michelle Jones, 31, and her children, Daniel Jr., 8, and Amanda, 3.

Pantazis was at home with her family 13 years ago when Souliotes’ son called her from Modesto.

Dad is in jail, he told her, and his face is all over the news. Her nephew said he wanted to call earlier, but his father figured the police would quickly realize their mistake and release him, she said.

Pantazis met with her brother the next day. He wore an orange jumpsuit and had tears in his eyes, she said.

“ ‘Aleka, I don’t know why I am here,’ ” she said he told her.

Souliotes, divorced, managed his rentals and spent his free time traveling to ballroom dance competitions with his girlfriend. The two were planning to visit Greece.

Pantazis sat through Souliotes’ two death penalty trials: The first jury hung 11 to 1 for conviction, prosecutors said, and Souliotes said he refused an offer of 15 years to life before the second trial.

An appellate lawyer who suspected Souliotes was innocent called the Northern California Innocence Project, which takes fewer than 1% of the cases it reviews. The Santa Clara University project is now trying to win Souliotes a new trial.

Police and fire records show the house was still smoldering that Jan. 15 when investigators began focusing on Souliotes. The landlord was behind bars by day’s end.

Investigators had a witness, Monica Sandoval, 19, who lived across from the burned house. At the time, she was facing a charge of assault with a deadly weapon.

Sandoval told investigators she stood on a balcony in the rain and cold from 1 a.m. to nearly 3 a.m. that day waiting for her boyfriend.

She said she saw a motor home or Dodge Caravan drive by at least 15 times before the driver parked, emerged carrying what looked like a pillowcase and headed toward the rental house.

She said he returned empty-handed and drove away. Minutes later she heard a “whoosh” and saw flames coming from the house, she said.

Handwritten notes from one of the first investigators who spoke to her described the vehicle as an “RV Dodge van type.” Sandoval described the driver as about 30 and skinny, and wearing glasses.

Souliotes was 56 and, according to his sister, did not wear glasses for driving. But one of his three vehicles was a Winnebago. Its top was ringed with 18 lights, which Sandoval had not noticed.

Sandoval also failed to pick out Souliotes in a photo lineup, and when police first drove her by Souliotes’ home, she said his vehicle, from the back, did not look like the one she saw.

After driving her to an RV sales lot, police returned to Souliotes’ home to have her examine his Winnebago again. This time Sandoval identified it. She said she had seen a “W” on the vehicle that night.

In court six months later, she pointed to Souliotes as the man she saw. The assault charge against her had been dropped.

Authorities said Souliotes burned the house for insurance money.

The Joneses had given him notice that November that they were moving. Souliotes said they owed the last month’s rent -- they disagreed -- and a court ruled for him.

The Joneses could not move as planned, and Souliotes agreed to let them stay through the holidays. He was to evict them a few days after the fire.

At the time of the blaze, Souliotes had a tentative deal to sell the rental for $83,000. The house was insured for its replacement value, about $97,000.

Souliotes’ defense expert testified at the first trial that the fire stemmed from a natural gas leak in the stove, which had a history of trouble. Defense lawyers did not call him during the second trial, even though they promised to in opening arguments. They rested after calling only one witness.

Stanislaus County Deputy Dist. Atty. David Harris, the prosecutor, mocked the expert’s absence, asking the jurors, “Where’s Waldo?” Harris had elicited testimony that a gas leak did not cause the fire.

Harris told jurors that a petroleum substance found on Souliotes’ shoes matched a compound that ignited the fire.

“The shoes tell the tale,” Harris said.

The substance on the shoes and the fire debris are now known to be chemically different and “could not have had a common origin,” said Lentini, the scientist who examined them for the defense -- a finding prosecutors do not dispute. Many kinds of shoes contain hydrocarbons, which produce the smell people notice when they enter a shoe store, Lentini said in an interview.

The evidence cited in the courtroom to prove the blaze was set -- deep charring, burn patterns and burned holes in the floor -- are conditions seen in accidental fires as well as arsons, Randy Watson, a nationally renowned fire expert who has no connection to the case, said in an interview. Without photographs and more information, Watson said he could not draw any conclusions about the fire’s origin.

Harris said he still has “no doubt” of Souliotes’ guilt. The government’s appeals lawyer said that other incriminating evidence remained “compelling.”

Souliotes said he has spent his time in prison learning to read and write in English and “playing the detective.”

Two hundred miles away in her Glendale home, his sister frets about missing a call from her brother as she awaits the 9th Circuit decision.

“I will never let any stone stay unturned if there is something maybe underneath,” Pantazis said. “What I live for is to see the day my brother will walk out. Whatever years he has left, at least he will be free.”

maura.dolan@latimes.com