Nothing is left to chance in the work to bring the dead back to their loved ones.
"Those poor guys are on their hands and knees, wading through soot," said Dr. Bill Inkster, an identification specialist with the British Columbia coroner's office.
"They look like 17th century coal miners by now, I'm sure, and brushing ashes (away) with paint brushes," he said in a telephone interview from Burnaby. "It's just plain hard work — meticulous, slow."
Search and rescue teams including specially trained police, firefighters and forensic anthropologists have been combing the debris in staggering heat for more than a week since Canada's worst railway disaster, so far resulting in the recovery of 38 bodies.
Of those, 12 have been identified at this point.
Officials let reporters close to the search area for the first time on Tuesday to give an idea of the destruction and the difficult working conditions.
Burnt oil tankers lay in a misshapen pile, still steaming with heat. Temperatures are estimated to be 10 to 20 degrees higher than elsewhere.
"We're doing building by building, very, very, very carefully," said Michel Brunet, a Quebec provincial police spokesman on Tuesday.
"It's very hot over there. We have to change our personnel every 15-20 minutes."
There are between 30 and 40 buildings in the search area.
When searchers believe they've found remains a forensic anthropologist, such as seen in the TV show "Bones," is called in to determine it is in fact a body. Afterward, the coroner is notified so the process of removing it, then identifying it, can begin.
Crews have an array of equipment at their disposal.
Some is as simple as a basic shovel or a brush. In other cases, it can involve huge construction excavators that can gingerly pick apart buildings making it safe for search crews to enter.
Besides helmets, crews are also garbed in coveralls and firefighting suits. Face masks and gloves are standard equipment and many wear air tanks because of fumes.
A chunk of Lac-Megantic's downtown core, which was dotted with bars, stores and homes, was obliterated early on the morning of July 6 when a runaway train loaded with oil derailed and exploded.
A tense vigil has been maintained in the days since as relatives and friends await word of their loved ones, now mainly to confirm their worst fears.
"The initial search is beyond comprehension," said Inkster, who was part of the team of specialists that worked in Thailand in the wake of the 2004 tsunami.
"It's going to be incredibly complex."
The director of the forensic-science program at the University of Toronto says a carefully co-ordinated team approach is being used in Lac-Megantic.
"The approach that's going to be taken is very similar to an archeological excavation, where you go through layer by layer, sorting and screening and carefully removing each level of debris searching for the human remains that may be embedded within," Tracy Rogers said.
Rogers, who helped identify remains found at the notorious B.C. pig farm of serial killer Robert Pickton in 2002-2003, said crews working in Lac-Megantic have to proceed carefully — not just to preserve remains and evidence but to protect themselves.
"They've got toxic areas, they've got hot spots. They've got all sorts of different things they have to address that's important for the safety of the searchers. When you have something like buildings going down, you get levels and levels of debris."
While the digging goes on, other experts come at the task from a different angle.
Police, for example, build a detailed missing-person profile that looks not only at the person's description but habits, such as where they were last seen or had they frequented spots in the disaster zone such as a favourite bar.
Authorities have also urged families of the missing to provide such things as tooth and hair brushes so they could get DNA samples.
Biological samples are taken from other family members for comparison, said Inkster. Medical records are invaluable, particularly x-rays and dental records.
While DNA can be compromised, teeth "definitely tend to survive," Inkster said.
"The two things that degrade DNA quickly are exposure to water and heat," said Inkster. "(But) enamel's the hardest thing in the body."
Yet DNA can't be underestimated and can be drawn from very small samples, said Rogers.
X-rays can provide invaluable clues.
"There are parts of the skeleton that are unique to the individuals," Rogers said.
For example, she pointed to the frontal sinuses, where most sinus infection occur.
Those spaces in the bone of the forehead are particular to their owner, like a set of fingerprints. However, their use in identification would rely on matching them to an X-ray that was done when the victim was alive.
Depending on what part of the skeleton is recovered it can also reveal an age-range, sex, ancestry and height, she said, which helps add potential pieces to the puzzle.
Geographic analysis also plays a role.
Obviously clues can be drawn to a body's identity when it's found in a specific house — such as the victim's own — and when looking at a timeline of where people went and were last seen.
Another challenge in such a catastrophic scene is separating the debris from the remains.
Both scientists agreed it takes expertise to tell the difference.
"It is very difficult," Rogers said.
"Different materials burn differently, leaving different kinds of residue or appearances. Sometimes it's that experience of looking for the difference in the texture that helps signal (that) this is not charred wood."
Both experts stressed that nothing is taken for granted and when a formal identification is announced, it is only done when the coroner is 100 per cent sure.
"That's why the biological evidence is so important."
And they added that even when it's impossible to identify someone, DNA is kept on file and periodically retested in hopes that a fresh set of eyes or new technology might provide an answer.
Inkster, who with his partner helped develop Canada's first database for unidentified remains and missing persons, said the Lac-Megantic disaster is unlike anything members of the Quebec team have ever practised or expected.
He was unshakable in his confidence that they would prevail.
"They'll absolutely get the job done, one way or another," he said. "I know they will. They're just excellent people."
(With a file from Benjamin Shingler in Lac-Megantic)