Julia Metzler, 3, was pronounced dead at 6:45 p.m. The cause of death was smoke inhalation, according to Morris County Prosecutor's Office spokesman Lt. Jeffrey Paul.
The toddler was found by Mendham firefighter William Taquinto using a heat-detecting sensor. She was rushed to Morristown Memorial Hospital and later helicoptered to Jacobi, authorities said.
An obviously saddened Taquinto Monday night could say only that he was, "Sorry we couldn't have found her faster."
Earlier Monday, investigators said a candle may have sparked the fire, although a cause had not officially been determined by Monday evening, according to the Prosecutor's office. Investigators "are looking at the possibility that a candle" led to a the blaze that seriously damaged the house at 85 Mountain Ave., Chief of Investigations Joseph Devine said through a spokesman.
Julia's mother, Margaret Metzler, escaped the blaze with her two other children, an 8-year-old boy and 5-year-old girl.
The parent was given oxygen at the scene, but she and her two other children were not injured, said Lt. Paul.
County Prosecutor Michael Rubbinnacio early Monday had said the youngest child was rescued "due to the heroic efforts of (firefighter) Taquinto."
The child's mother told firefighters that she mistakenly thought her youngest child had been running from the home with her two siblings.
"She thought they had all followed her out the door," said Taquinto, a 7-year firefighter.
Taquinto used a 9-pound thermal imaging device to locate the unconscious girl under her bed on the second floor after a frantic search lasting about 10 minutes.
Taquinto, in a Monday afternoon interview, said he first checked the kitchen, where the girl's mother said she last saw her daughter, and then the nearby basement. He then checked the girl's bedroom, where her slumped form was clearly visible through the lens.
"When you go through the (county fire training) academy, they teach you that nine times out of ten, the child will be in a closet or underneath their bed," he said.
By coincidence, Taquinto, an employee of Mendham's public works department, and other Mendham firefighters had been in a nearby field Sunday evening, overseeing the disposal of Christmas trees, when they received the fire call.
Taquinto said he had used the device - purchased in 1999 for about $16,000 - previously to locate hot spots in walls, but never to locate a missing person. Without it, he said he never would have been able to spot the fallen child.
He spoke of the "urgency" that sets in during such searches.
"Just knowing from your training, that you're on a time limit, and it's not that much time," he said.
Edward Metzler, who earlier left to pick up dinner for his family, pulled up in his car just as the first fire trucks were reaching the scene, said Mendham Fire Chief Joe Eible.
The blaze was brought under control in about an hour. One Mendham firefighter was treated for a minor hand injury, Eible said. Approximately 60 firefighters from Chester, Mendham Township's Ralston and Brookside departments, and Mendham responded to the scene.
Rubbinaccio announced that smoke detectors in the house had been in working order and were activated by the blaze.
On Monday morning, two Mendham police officers kept watch over the home, which was cordoned off in yellow tape. A baby swing was visible suspended from a front yard tree limb.
Officials said the house sustained significant heat and smoke damage. The fire was mostly confined to the kitchen but a few flames made it to the second floor, Eible said.
According to the borough tax assessor's office, the Metzlers bought their home in 1995.
