Investigators with Jackson County Fire District No. 5 have finished their investigation without finding a clear cause of an intense fire that destroyed the Colver House in Phoenix Sept. 14.

Investigators with Jackson County Fire District No. 5 have finished their investigation without finding a clear cause of an intense fire that destroyed the Colver House in Phoenix Sept. 14.

The cause will be listed as undetermined, leaving the case open to further study, and Oregon State Police and state fire marshal investigators will continue the work, District 5 Chief Dan Marshall said.

The charred facade of the 153-year-old building 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. Foreclosure documents filed in April noted a failure to keep the property insured as required under the terms of the Greers' loan.

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, Marshall said. The rapidly developing fire spread through wood stored there and the rest of the wooden structure, then caused the rupture of natural gas lines behind the house.

Avista sent experts whose tests determined that the natural gas fire erupted in the growing conflagration and didn't start the fire, Marshall said. Natural gas service to the home had been turned off at the gas meter for about a year and past excavation had exposed the underground pipes, he said.

The charred hulk of one of the oldest structures in the Rogue Valley, built in 1855 as the Rogue Indian Wars drew to a close, is now surrounded by temporary fencing to keep people away from the blackened timbers and chimneys. 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.

— Anita Burke