That was the first clue - though not the only one - that the Feb. 19 fire in Lawrence that killed a mother and three of her children was arson, set using an accelerant, investigator George Laasko testified.
Laasko testified on the third day of probationary volunteer firefighter Caleb Lacey's trial on arson and murder charges. Prosecutors have said Lacey set the fire, then reported immediately to the Lawrence-Cedarhurst firehouse so that he could help fight it and look like a hero.
Lacey's lawyer, Christopher Cassar, has not disputed that the fire that killed Morena Vanegas, 46, her son Saul Preza, 19, and daughters Andrea, 10, and Susanna, 9, was arson. He says it was not his client who set the fire.
Laasko testified that by walking through the apartment in the hours after the fire, he could tell the blaze had not started in any of the rooms there, because the damage was not severe enough.
The worst damage in the building was in the front entranceway and on the first four stairs leading to the two second-floor apartments, he said.
His suspicions were confirmed, he said, when the local fire marshal brought to the building a dog trained to sniff out accelerants such as gasoline and lighter fluid. The dog, called "Canine Abby," led authorities straight to the foot of the staircase, he said.
Gasoline was found in Lacey's fire pants after the fire, police and prosecutors have said. Cassar says Lacey ran a tree-trimming business, and used gasoline all the time.
Laasko, who is expected to continue testifying Thursday, also said fires that are started using an accelerant tend to begin with a sudden flash of flame.
Prosecutor Michael Canty introduced a surveillance video taken by a nearby store owner at 5:38 a.m., when the fire is believed to have started, that shows a big flash of light reflected in trucks that were driving by the house that burned.
Morena Vanegas' husband, Edit Vanegas, escaped the fire by jumping out a rear window with his two sons, who were 9 and 12 at the time.