PHOENIX — Fire investigators couldn't find a clear cause of an intense blaze that destroyed the historic Colver House.

PHOENIX — Fire investigators couldn't find a clear cause of an intense blaze that destroyed the historic Colver House.

Investigators from Jackson County Fire District No. 5 and the state fire marshal's office finished their investigation and concluded that the cause of the Sept. 14 fire is undetermined. Officials said insurance investigators plan to look further.

"We might never really know because of the damage," said Charlie Chase, a deputy state fire marshal.

Investigators found a list of possible causes, but couldn't conclusively confirm or eliminate any of them, he said. The home's owners, Jennifer and Jerry Greer, are both smokers, Chase said.

Jerry Greer had a woodworking shop with saws and other equipment, and in the weeks before the fire he had been finishing wood with linseed oil, which can spontaneously combust. The 153-year-old home's electrical system could have had problems.

Chase said he didn't see anything unusual at the fire scene that led him to suspect arson.

Phoenix police stepped in to help fire investigators by interviewing witnesses, but Chase said no criminal investigation was under way.

Investigators confirmed that the fire likely started in the rear part of the house on the first floor, which was used as a woodworking shop and storage area, Fire District 5 Chief Dan Marshall said.

The rapidly developing fire spread through wood stored there and the rest of the wooden structure. Flames probably climbed inside a wall up to the attic and burst through the roof, Chase said, noting that damage seemed more intense on the ground floor and in the attic than on the walls of the second story.

The raging fire caused a breaker panel to crash onto a natural gas line behind the house, Chase said. The severed gas line spewed fuel onto the fire for about two hours before Avista utility crews could dig up the line in front of the house and crimp it to cut off the gas supply.

Natural gas service into the home had been turned off at the gas meter for about a year and past excavation had exposed the underground pipes, Marshall said.

"With the gas spraying in there, we couldn't tell anything," Chase said.

The charred facade of the building at 150 S. Main St. has been turned over to State Farm Insurance, the owner's insurance company, Marshall said. Cory Dalpra of Talent is the listed agent, but his office would neither confirm nor deny any details about insurance coverage or a continued investigation by the company. State Farm claim adjusters also have declined to return calls to the Mail Tribune.

Foreclosure documents filed in April noted a failure to keep the property insured as required under the terms of the Greers' loan, but no other details about insurance coverage of the home are publicly available. A foreclosure sale originally set for Sept. 19 to pay off a $240,000 loan has been postponed until Oct. 6.

Fire officials have said that investigators working for State Farm plan to use heavy equipment to get under collapsed beams and delve deeper for evidence about the fire. The Phoenix building department reported that no permits are needed for cleanup or investigation at the site of a house fire.

The charred hulk of one of the oldest structures in the Rogue Valley, now surrounded by temporary fencing to keep people away from the blackened timbers and chimneys, has been handed over to the insurance company team, fire officials said.

The Greers were at home when the fire broke out and were injured when they jumped from a second-story window. Jennifer Greer has been released from Providence Medford Medical Center, but Jerry Greer remains hospitalized in good condition at Legacy Emanuel Hospital and Health Center in Portland.

The home the Greers have owned since 1989 was built in 1855 as the Rogue Indian Wars drew to a close. Other buildings from that era include the Birdseye House, an 1856 home restored after a 1989 fire, and the Mountain House, along old Highway 99 in Ashland, started in 1851.

Reach reporter Anita Burke at 776-4485, or e-mail aburke@mailtribune.com.