CONCOW, Butte County — Victim No. 53 was pulled from the rubble of someone else’s life.

One year after the historic Camp Fire blasted through the Sierra Nevada foothills, 84 people who died in the flames have been identified. But one person endures as a mystery — a man whose remains were found in the scorched footprint of a mobile home, burned beyond recognition, in this tiny community just east of Paradise.

He may have died a hero. And we may never know his name.

In the wake of the fire that swept through Butte County on Nov. 8, 2018, the worst blaze in California history, Victim No. 53 was carefully unearthed from the property on Schwyhart Lane in Concow. How did he come to be there? No one knew.

This was the home of Lon and Ellen Walker. They’d been married for 30 years after meeting in 1988 in Napa. Lon was a truck driver, Ellen a medical transcriber. Both had been married before. On their first date, they simply met up and chatted in the 1976 station wagon Ellen had driven west from Ohio. They moved to Concow to retire.

Walker holds a photo of Ellen, 73. The remains of Victim No. 53 were found with hers.

(Santiago Mejia / The Chronicle | San Francisco Chronicle)

On the morning of the fire, Lon, 76, picked up a load of lumber in Plumas County. He had been about to quit his trucking job so he could take care of Ellen, who at age 73 suffered from fibromyalgia and didn’t like using her walker. She moved slowly about their place, tending to the fruit trees and four cats. The calico, Ginger, was her favorite.

The fire that ignited around 6:15 a.m. under Pacific Gas and Electric Co. transmission lines moved quickly, traveling west nearly 3 miles to Concow within an hour. Ellen was among many people the fire trapped in their homes and cars.

Lon feared the worst, that she’d indeed died in the fire. But when confirmation of her death came, weeks later, there was also a strange piece of news — the presence of Victim No. 53.

The two victims’ bodies had appeared to be one, until anthropologists from Chico State University distinguished three kneecaps among the remains. A year after he was found, authorities still have few clues to who he might be.

But they’re determined to somehow give him a name and deliver him to his family.

The site of the Walkers’ mobile home on Schwyhart Lane in Concow. After 30 years of marriage, Lon was going to stop working to help Ellen, who used a walker.

(Photos By Santiago Mejia / The Chronicle | San Francisco Chronicle)

To identify the victims of the Camp Fire, authorities had to search more than 19,000 ruined structures for bodies, the biggest operation of its kind in state history. Meanwhile, at one point, the number of missing-persons reports connected to the blaze swelled to more than 10,000.

Bone often resembles construction materials, and as anthropologists separated bits of Sheetrock and ceiling panels from recovered skeletal fragments, they learned that investigators in the field weren’t always able to discern between them. The presence of animal bones and cremation urns destroyed in the fire complicated matters.

Occasionally, multiple victims were accidentally lumped together, or a single victim’s remains were separated, causing the death count to fall or rise. What had come to them as Ellen’s remains, anthropologists soon realized, were actually those of two people — though only one had been reported missing at that location.

No unclaimed vehicles were found near the mobile home on Schwyhart Lane. And no men with links to the area were unaccounted for. One guess was that Victim No. 53 might have rushed in to try to save Ellen from the advancing flames, losing his life trying to do a good deed.

“I don’t know why he was at the house,” said Sacramento County Coroner Kim Gin, whose office did autopsies of most of the Camp Fire victims. “Nobody knows who he could possibly be. We can go years without knowing who someone is. It’s one of these cases that is going to take quite a bit of time to get an answer, if we ever do.”

Some officials believe Victim No. 53 — his designation at the coroner’s office — might have been a migrant worker from a nearby marijuana farm. Perhaps, they speculate, he had seen her gardening in the past, knew she was disabled, so tried to save her.

“This is our mystery guy,” said Jennifer Celentano, the coroner’s investigator for the Butte County Sheriff’s Office. “He had no reason to be there. We don’t know if maybe he came up to trim plants and was running from the fire, or knew there was an elderly woman that needed help. It’s a mystery.”

Sacramento County Coroner Kimberly Gin and her team use the walls in this hallway to keep information organized to identify the Camp Fire victims. Each poster represents a person.

(Santiago Mejia / The Chronicle | San Francisco Chronicle)

After the Camp Fire, officials turned to Boston-based ANDE Corp., which volunteered its “Rapid DNA” technology to Butte County and identified 23 victims in the first month. A mobile resource center was set up in Chico, where families of missing persons could swab the insides of their cheeks to provide matchable genetic samples.

Law enforcement officers from as far away as Tennessee and Virginia helped collect DNA from potential relatives of victims who lived far from Butte County. But as the count of unidentified victims went down, No. 53 stayed nameless.

“It’s quite possible that the family of this unfortunate person has no idea that he was ever in California,” said Richard Selden, ANDE’s founder and chief scientific officer. “Maybe the biological relatives don’t even know the person is missing. There are probably a dozen family members who are wondering why their loved one stopped communicating with them.”

About 90% of Camp Fire victims were identified using Rapid DNA testing. At times, though, a DNA sample salvaged from the fire was too damaged, and Selden couldn’t distinguish genetic markers. Victim No. 53 was one of those cases.

Authorities often could make an identification by examining other elements in the remains, like teeth fillings or hip and knee replacements. Family members assisted in gathering dental and medical records. But none of those methods were helpful in the case of Victim No. 53, so Selden turned to a full DNA sequencing.

This more elaborate laboratory analysis takes weeks and can reveal clues such as a person’s gender and approximate age. But it doesn’t guarantee a match — and it didn’t for Selden’s mystery man.

“Just because you get a result doesn’t mean you automatically know who this is,” Gin, the Sacramento coroner, said. “You have to put regular investigative work into it once you get that potential hit.”

A makeshift memorial in Paradise commemorates the 85 people killed in the Camp Fire. Each victim but one has a name. Did he die trying to save Ellen Walker?

(Photos By Santiago Mejia / The Chronicle | San Francisco Chronicle)

This fall, the case of Victim No. 53 landed with Margaret Press, the co-founder of the DNA Doe Project.

The organization in Sebastopol takes on investigations that have eluded coroners. It works in the field of genetic genealogy, which combines DNA testing with the type of research people use to build family trees, and was central in leading to the arrest last year of Joseph James DeAngelo, the suspected Golden State Killer who terrorized California in the 1970s and 1980s.

Press uses GedMatch, a website that compares DNA to offer a percentage likelihood that two people are related. Parents and children share 50% of their DNA, as do siblings. That number drops to 25% for grandparents and 12.5% for cousins. For Victim No. 53, Press hopes to find, if not a first cousin, perhaps a third cousin that shared the same great-grandfather.

Little by little, she is trying to zero in on his identity. But there’s an obstacle: Since it was revealed that GedMatch helped investigators find DeAngelo, the website changed its rules to satisfy privacy concerns. Now, users must opt in to helping with law enforcement cases, like the one Press is pursuing, and many opt out.

So Press can see only one-tenth of the database of 1.5 million people — a small fraction of possible relatives of Victim No. 53.

“They tipped over the apple cart, and there was outrage rippling through the community that threatened websites’ ability to stay up for genealogy purposes,” Press said. “It has polarized people in a sad and sometimes toxic way. As a little tiny community, we are struggling with how to resolve these issues.”

The Butte County Sheriff’s Office continues to probe the mystery of the unidentified victim as well, but deputies have had difficulty finding people with good information.

In the meantime, the county turned the dead man’s case over to a state-appointed public guardian, who is suing PG&E on his behalf. Any settlement would be passed on to his relatives — if authorities ever locate them.

“This is such an unusual circumstance,” Press said. “Everybody should have a name and be returned to their family. It’s something, as a species, we have done ever since we have had names. This man’s family is, metaphorically, parked outside a coroner’s office, unable to even get a death certificate right now.”

Lon Walker, 76, moved to the Chateau Senior Mobile Home Park in Oroville after Ellen died at their home in Concow. Walker takes some satisfaction knowing his wife didn’t die alone.

(Santiago Mejia / The Chronicle | San Francisco Chronicle)

One year after the Camp Fire killed his wife and a man who may have tried to help her, Lon Walker is trying to move on.

He remembers how Ellen was a “proper lady,” never uttering a single curse, as far as he knew. How she wore pretty clothes, loved singing in the church choir and regularly got her hair set at Ultimate Cut in Oroville. How he was so close to hanging up his trucking job for the season, just to stay home with her.

“She was my everything,” he says. “We had a beautiful life together in Concow, with trees and flowers. I’ll tell you what, she left a wonderful legacy for this old man. I was looking forward to spending the rest of our lives together, until we were old and tired, or maybe just old.”

He paused.

“If I had been there … if I had been there, this wouldn’t have happened. My heart aches and breaks not being the man I should have been. It still hurts me after all of this time, and it hasn’t been that much time.”

Since the fire, he’s moved to a retirement community in Oroville, transplanting a few of his wife’s bushes to his new front yard, something to remind him of their home. Lon is grateful that his wife didn’t die alone. But he wants to know just what happened as the Camp Fire roared toward Schwyhart Lane.

“It goes beyond imagination,” he said. “I have to find some answers.”

Lizzie Johnson is a San Francisco Chronicle staff writer. Email: ljohnson@sfchronicle.com Twitter: @lizziejohnsonnn