Fire officials picked through the ashes in seeking the cause of a suspicious fire that destroyed a vacant house at 20 Castle Hill Road, early on the morning of Wednesday, May 25.This is an updated and expanded version of a story originally published at 9:16 am Wednesday, May 25.

Town Fire Marshal Bill Halstead said he expects that someone intentionally set the fire that destroyed the 1908 house at the 66-acre site owned by Castle Hill Real Estate Holdings, LLC. The property has a second building, also constructed in 1908, that was not affected by the fire.

There were no injuries.

"This was a set fire. It's definitely an arson," Mr Halstead said. He added, however, that he is researching whether a lightning strike might have caused the fire, in order to rule out that possibility.

The 5,703-square-foot house, which had been vacant for many years, did not have electric service, he noted. The house was not insured, he said.

Mr Halstead said the fire was so intense that physical evidence which might have been useful in probing the cause of the blaze was destroyed in the fire.

Mr Halstead called in the state fire marshal for investigatory assistance. The state fire marshal used a dog to sniff outside the building in seeking to learn whether any fire accelerants were used, but no traces of accelerants were found, Mr Halstead said.

No point of origin for the fire was found, he added.

In order to fully put out the fire, the building needed to be demolished, Mr Halstead said. Thus, fire investigators were not able to get inside the structure with the fire marshal's dog to check for evidence.

Town police Detective Jason Frank is aiding in the probe and will be questioning people who may have knowledge of the incident, Mr Halstead said. Det Frank is a deputy fire marshal.

Det Frank is expected to talk to the property's owner, Mr Halstead said.

Det Frank said May 25, "We have some leads. We're investigating the leads." Police are conducting interviews in the case, he said.

A caretaker atop the hill at Newtown Forest Association's Holcombe Hill Wildlife Preserve, which lies about two miles southwest of the fire scene, called the town's emergency dispatch center to report seeing a glow and possible fire, after which Hook & Ladder volunteer firefighters were dispatched to the area to investigate, Mr Halstead said.

Police informed the firefighters who were traveling to the scene that a house was on fire.

Volunteer firefighters from Sandy Hook, Dodgingtown, Botsford, and Hawleyville also responded to the scene. Stony Hill and Stevenson volunteer firefighters made mutual aid calls to the fire, and Brookfield and Bethel firefighters provided coverage at fire stations in Newtown.

Jason Rivera, Newtown & Ladder's first assistant chief, was the incident commander.

He said that on his arrival, "There was fire out every window on both floors." He estimated that the fire was burning for "a significant amount of time" before it was discovered.

Firefighters used water drawn from hydrants in the area, which was then shuttled to the scene in fire tanker trucks, to put out the blaze.

Asst Chief Rivera estimated that about 30 firefighters responded to the 1:50 am call. The blaze was declared under control at 4:15 am.

Firefighters stayed at the scene until late Wednesday morning, spraying water on smoldering hot spots that remained amid the building's ruins.

In April 2013, Newtown resident Joseph Draper purchased the property and the adjacent land at 60 Castle Hill Road from the Bridgeport Catholic Diocesan Corporation.