Almost a year after the Asian tsunami, just six families of Britons known to have died are still waiting for their loved ones to be identified and brought home. BBC News talks to the man responsible for the identification operation.
Det Supt Walker has acknowledged the human cost of his work
Detective Superintendent Graham Walker may be a hardened Metropolitan Police officer who has seen it all.
But not even the harrowing experience of some of Britain's worst rail and fire disasters could prepare him for the devastation of the Asian tsunami.
"You can train for it, you can practise, but when a catastrophic event occurs - you're in a whole different dimension," the man chosen to lead Britain's recovery team in the disaster zone said.
"I left with some preconceptions about the area and environment I was going into - but I have to say it took me totally by surprise."
By the time Mr Walker and his victim recovery team arrived in Thailand a week after the tsunami struck, thousands of bodies had been collected and decomposition was well under way.
He said that the scene that greeted him was beyond horrific.
Bodies tied together by their limbs to stop them being lost floated in the now gently lapping sea, lacerated suitcases from beach bungalows were swept miles inland and children's shoes lay eerily on the pummelled beaches.
"At Khao Lak - the main scene of devastation and death - the Thais had taken all the bodies to the nearest temple," Mr Walker said.
"We ended up with about 2,000 decomposing bodies lying in the sun."
His task was to identify the British victims, retrieve their bodies and return them home if that was desired.
It was a mammoth challenge - initially some 8,000 Britons were reported missing.
Meanwhile, the thousands of bodies collected by Thai police and volunteers were deteriorating in makeshift mortuaries along with crucial DNA clues to their identities.
Mr Walker says it quickly became clear that identification was going to have to be an international effort.
Bodies were stored in makeshift mortuaries
The level of deterioration and the scale of the injuries made it impossible to differentiate between the races of the victims.
And it wasn't just the scale of the job - the conditions in which Mr Walker's team had to work included live wires, rabid dogs and temperatures of 50C.
By the end of the first day, 60 of his team members were wounded in various ways, 50 had vertigo, 45 were suffering headaches and one person had sustained a head injury.
For the first few weeks the team barely slept.
'Manifestation of grief'
They had to work fast to prevent the false identifications which had been made in the first few days ending in a second disaster.
"Before we arrived... a number of people said "That's my partner" or "That's my child". But one in 10 of these were erroneous," he says.
The Thais took as many bodies as possible to temples
"For example there was a dead loved one brought back to England after an unofficial ID.
"When she arrived forensic tests showed that she wasn't the person she had been believed to be."
He cites another case of eight different families claiming one victim as their loved one.
Mr Walker does not blame these bereaved families looking desperately for their family member.
"There is a distortion, people just see what they want to see - we just know that that's how grief manifests itself," he said.
But he says it underlines how important it is to follow the international protocols of the Disaster Victim Identification procedure.
This requires scientific identifiers such as fingerprints, DNA, dental records or the presence of a unique medical condition to be matched in individuals before and after death.
But before this painstaking forensic work could take place, officers had to narrow down the list of potential victims from the initial 8,000 to a more likely figure.
After investigation at the British end, a list was eventually drawn up of those deemed highly likely to have been involved in the tsunami.
Then pre-death forensic evidence had to be collected by officers working alongside family liaison teams.
Most were identified through dental records but in a number of cases detectives had to use more unusual methods such as dusting for finger prints from a much-loved, but little read university thesis.
Mr Walker's team had to "think outside the box" to get samples.
But, as a result of that innovative and painstaking work, they were now only "a small number" of outstanding identifications, he said.
There are just six of the 141 UK citizens known to have died in the disaster whose bodies have not been identified.
Most European identifications were made through dental records
Mr Walker says he was never daunted by the scale of the task.
"I believed all the way through that we would be able to say, 'If your loved one was here then we will find them'.
"If we haven't found them and they were here then I have to surmise they were lost to the sea. But we will not stop until we have reached that point.
"We can only apologise for the time it takes - but I can assure you it's not through the lack of effort or dedication."
Some 900 bodies remain in Thai mortuaries awaiting identification and the DNA work is still going on.
The majority are believed to be Thai or Burmese - perhaps 100 will be European.
But at some point the British operation has to come to end and that point appears to be just around the corner.
The team is in the process of transferring responsibility to the Thais and it is thought that by the end of February there will no longer be a need for British staff to remain.
But Mr Walker stressed: "There will be in place somebody to inform the families until the last person is identified and there is nobody else to look at, no matter how long it takes."