The 15-foot Fraser fir that twinkled with Christmas lights was showing its age. After six weeks on display in the castle-like mansion overlooking the water in Annapolis, the tree’s branches were sagging, and its needles had become brittle.

The fir was supposed to come down Jan. 20. But the night before it was to be removed, it became the tinder fueling a powerful blaze that consumed Don and Sandra Pyle’s home, leaving the couple and four of their grandchildren dead.

That the Christmas tree was slated to be removed the day after the blaze was yet another devastating detail that emerged Wednesday from a report investigating one of the deadliest fires Maryland has seen in decades.

“That was one of the worst pieces of information that came out of this,” said Dave Cheplak, a spokesman and special agent for the Bureau of Alcohol, Tobacco, Firearms and Explosives field division in Baltimore.

Authorities with the ATF and the Anne Arundel County Fire Department issued the 43-page report about seven months after investigators declared that an electrical outlet powering tree lights overheated, igniting a tree skirt and leading to the inferno that killed Don, 56, and Sandy Pyle, 63. Two sets of Boone siblings — Lexi, 8, and Katie, 7, and Charlotte, 8, and Wes, 6 — also died in the blaze.

In this video released by ATF, there's an example of 360-video imaging used by fire investigators to capture the scene after the Annapolis mansion fire on Jan. 20, which left six members of the Pyle family dead. (ATF)

“According to interviews, the tree located in the Great Room was steadily dropping needles and the branches had started drooping,” the report said. But “Don and Sandy Pyle both wanted to keep the tree in the Great Room longer because they felt like they hadn’t had a chance to enjoy it.”

On the night of the fire, smoke alarms in the home were functioning, but because the brittle tree provided such a massive fuel load, the fire quickly swept through the house, leaving the family unable to escape.

“The whole sequence of events was horrendous,” said Capt. Russ Davies, a spokesman for the Anne Arundel fire department.

More than 230 firefighters, investigators and law enforcement officials from across the region were involved in putting out the blaze or searching for bodies in the charred rubble of the 16,000-square-foot home. Over days of painstaking work, investigators found the four children and their grandmother in guest bedrooms on the second floor of the home, according to the report. Don Pyle was found in the Great Room of the home where the tree decorated in 15 strands of glowing lights lit 24-7 once stood.

“Males tend to attempt to extinguish a fire, whereas females attempt to save their family members or victims,” Cheplak said. “Donald ran downstairs thinking he could somehow extinguish the fire but was overcome very quickly.”

Two 15-foot Fraser firs, similar to the one on display in the Pyle home, were set on fire at the ATF Research Lab in Beltsville, Md. The tree to the right, which was watered daily, ignited in less than seven seconds. The tree to the left, which was watered weekly, took five minutes to ignite. (ATF)

The report also detailed work that ATF researchers conducted after the fire. Investigators ordered three Christmas trees similar to the one in the Pyle home and conducted controlled burns at their laboratory in Beltsville.

The trees watered weekly ignited in five to 30 seconds, according to the report. But a tree that was watered daily took about seven minutes to catch. The two trees watered weekly were consumed in less than a minute, while the tree watered daily extinguished on its own.

The tree in the Pyle home was watered about once a week, officials said.

Although authorities were careful not to place blame or point fingers, they said the tragedy offers lessons for others.

“Certainly that’s not a good idea to keep a tree much past New Year’s Day,” Cheplak said, “but if that tree had been watered on a daily basis, it would have made a significant difference.”

The Boone and Pyle families, through a spokeswoman, declined to comment on the details of the report.

Cheplak said it was difficult for the family and investigators to go over the details of the report Tuesday night and relive the pain of the fire.

“I think they came away from it with a better understanding of why this happened and how it happened,” Cheplak said, “and that is all we can hope for.”