North Bay fires a complex puzzle for investigators seeking answers on cause

GLEN ELLEN - Sonoma Valley sculptor Bryan Tedrick has long found inspiration here on a remote piece of creekside land, where he shapes oversized figures of metal, stone and wood. Lately, this quiet meadow rimmed by forest has drawn an unusual group of visitors.

Tedrick said “layers of investigators” have combed this area off Nuns Canyon Road since an unprecedented firestorm erupted Oct. 8, destroying his workshop as it ran roughshod over 142 square miles of Sonoma County.

State authorities and contract investigators have planted colored flags, taken measurements, shot pictures and scrutinized an area about 100 feet from Tedrick's rented shop, where a corrugated metal pump house and charred utility pole sit amid blackened tree trunks above the banks of Calabazas Creek.

The vicinity is one suspected point of origin for the Nuns fire, the largest of several devastating blazes in Sonoma County that broke out nearly three weeks ago and are set to be fully contained Tuesday.

Including the deadly Tubbs fire, which began near Calistoga and burned through northern Santa Rosa, the blazes destroyed 6,957 structures in the county - most of them homes - and killed at least 23 people. Preliminary damage estimates top $3 billion.

Closely guarded job

Since nearly the first hours of the wind-whipped disaster, officials have been trying to determine how the fires started near Glen Ellen, Calistoga and other areas in Wine Country. More than a dozen fires erupted that night across the North Bay; the deadliest, the Tubbs fire, made a 12-mile run from Calistoga into a north Santa Rosa neighborhood in just over four hours.

The investigation is a closely guarded job done by a tight-lipped network of experts. They collect physical evidence - some of it microscopic - conduct interviews with witnesses and use high-tech equipment to try to pinpoint the origin of flames that swept over vast landscapes, consuming much in their path.

“Our No. 1 objective is we want to get it right,” said Cal Fire Deputy Chief Ron Eldridge, who leads the agency's Southern California law enforcement division and has about seven investigators assigned to fire probes in the northern part of the state. “It's going to take time, and we're going to very methodically work our way through that investigation to make sure we put out the best available investigation.”

The high-stakes role for Cal Fire, the state forestry and firefighting agency, is to determine if any of the fires may have been caused by criminal conduct or negligence, and if so, by whom. Any findings could lay the groundwork for subsequent civil proceedings or criminal prosecution, Eldridge and others said.

Developing a picture

The investigations could be a factor in third-party cases, which have already started to emerge in Bay Area courts. A Santa Rosa couple filed suit earlier this month in San Francisco against PG&E, claiming the utility is responsible for the Tubbs fire that destroyed their Coffey Park home and thousands of others in Sonoma County. The suit alleges the company failed to maintain and repair high-voltage power lines, which the couple claims came into contact with parched vegetation, starting the Tubbs fire and several others still burning in Wine Country.

Winds gusted above 60 and 70 mph in some parts of the county the night of the firestorm, when downed power lines were reported across the region. Atop Geysers Peak, sustained winds were measured at 94 mph, with gusts as high as 108 mph, Cal Fire spokesman Jonathan Cox said.

“The winds, along with the millions of trees weakened by the years of drought, all contributed to some tree branches and debris impacting our electric lines across the North Bay,” said Deanna Contreras, a PG&E spokeswoman.

All such instances have been reported to state utility regulators, Contreras said, and PG&E is cooperating with state investigators.

“We're not going to speculate about a cause,” she said. “Our focus is real answers.”

Fire investigators are stressing the same message: They have to remain open to all possible causes.

Cal Fire spokesman Scott McLean said 26 members of Cal Fire's law enforcement branch, which employs 193 investigators, are taking part in efforts to pinpoint the origins of each individual fire and determine their causes.

Four U.S. Forest Service investigators also have been sent to help, according to Kevin Mayer, an assistant special agent in charge with the Forest Service's Pacific Southwest Region. It is common in such wildfire disasters also to engage experts and consultants in various fields to develop a complete picture of how each fire got underway, officials said.

“It's tedious work,” said Paul Steensland, a former Petaluma resident and retired Forest Service senior special agent/fire investigator. “If it's done right, it's very slow.”

The first imperative is to protect the evidence, which is sometimes a big task, given the disruption that can come with firefighting activities, said Mayer.

Each suspected point of origin “is a crime scene until we determine otherwise,” Eldridge said.

That remains the case at Bennett Lane and Highway 128 in Calistoga, where the 36,807-acre Tubbs fire launched its deadly rampage into Sonoma County between 9:30 and 10 p.m. Oct. 8. There, strips of yellow crime tape this week barred entry to two driveways leading up the side of a wooded hill overlooking vineyards in autumn colors. Private security guards working 12-hour shifts blocked one of the driveways, protecting evidence within for Cal Fire, according to one of the guards. Additional yellow tape encircled a utility pole and other debris at the base of a charred hillside farther along the road.

‘It was jaw-dropping'

Residents of the semi-rural neighborhood at the western edge of Napa County were among the first to confront the inferno - now California's most destructive on record. Those early hours unfolded in a chain of panicked calls from neighbors, flashing sirens and eventually, the evacuation of tens of thousands of people.

Retirees Pat and Jim Pence were back home on Bennett Lane this week when they recounted a terrifying flight from flames Oct. 8 that destroyed most neighboring homes. Winds were so strong at the time, the couple recalled, they could barely stand up.

A power outage earlier that night had sent them to bed about 9:30 p.m. A short time later, a neighbor called to warn them of a fire on the hill. “It doesn't look good,” Pat Pence, 82, recalled the neighbor saying. About five minutes after that, the man called again, saying, “You'd better go.”

They did, and their house of nearly four decades survived after the fire stopped at a statue of the Virgin Mary a few yards off their back deck.

A short distance away, at 9:53 p.m. that night, Paul Block was alerted by a neighbor at his home and wine barrel furniture shop off Highway 128 just south of Bennett Lane.

He came outside into howling wind and looked up at the hill. “It was jaw-dropping,” Block recalled. “Big flames. The wind was insane.”

He also noticed areas where flames hugged the ground, “kind of crawling their way west.”

Mapping burn patterns

Those differences in fire behavior leave behind critical markers investigators use to map burn patterns, allowing them to narrow down the precise location where a fire started and trace the effect of slope, winds and fuel on flames, said Steensland, the retired Forest Service investigator. Since even the largest wildfire typically starts slow and low in intensity, there may be well-preserved, tell-tale evidence at its origin, he said.

While interviews with witnesses or firefighters first on scene can point investigators in the right direction, experts said, nature retains other clues. They include scorch marks on surfaces exposed to direct flames, ash deposits and sooting on trees or other objects in the fire zone, and even grass stems that can have distinctive burn patterns depending on the type of fire activity, experts said.

On the ground, investigators may use a magnifying lens, metal detector or magnet to search for evidence, including signs of human disturbance that would point to an accident or arson as a fire's possible cause, authorities said.

Exploring all angles

Pulsed laser, or LIDAR, instrumentation is also used to precisely measure a burned scene, which can later be modeled with computers to replicate how it would have looked before flames arrived, Eldridge said.

Investigators will typically interview as many witnesses as they can, including 911 callers, and review dispatch records, Eldridge said.

They'll consult weather records and meteorologists, and pore over maintenance records for the power grid and other mechanical systems in use near a fire's origin, experts said.

Conclusions typically don't come from authorities until they release a final report.

In the case of Lake County's devastating Valley fire in 2015, that report was made public 11 months after the blaze, which killed at least four people and destroyed nearly 1,300 homes. It was started by faulty hot tub wiring, Cal Fire investigators determined.

Mayer, the Forest Service special agent, likened a fire investigation to a homicide case, where “you can't stop looking for information or explanations” until all possible angles are explored.

“We want to make sure that we follow every lead that we can to see what it leads to,” Eldridge said. “Some go quickly. Some take a lot longer.”