Forensic experts have spoken of the extraordinarily complex investigation that lies ahead at Grenfell Tower and predicted that establishing the causes of the devastating fire will take months.

In the coming days, recovering victims’ remains would be a priority, they said, as investigators work against the clock to complete their search while the building remains structurally sound.

Emma Wilson, a fire investigator at Prometheus Forensic Services, said: “Investigators won’t stop until they have everybody who is missing or was known to be inside. They will check every area. They will ensure recovery of every person in there.”



Simultaneously, forensic scientists will establish a point of origin for the fire, and also reconstruct its rapid spread, meticulously documenting every piece of evidence that could help explain how the tragedy unfolded and whether it could have been prevented.

Wilson, who was an investigator at the scene of the Lakanal House fire, described the task of recovering remains as deeply upsetting. “Nobody who has seen anything like this would tell you any different,” she said.

In the upper floors of Grenfell tower, where the fire is thought to have been most intense, victims’ bodies could be severely damaged and under deep layers of debris and ash. Search dogs will also be used to locate remains.

However, even in the most devastating fires, it is normally possible to identify every individual and reunite their remains with relatives through DNA testing. “The victims must be forensically recovered to ensure you have the right people identified and that they are taken care of and given the dignity that they deserve,” said Wilson. “I’ve never come across a case where [this] wasn’t possible.”

DNA analysis can typically be carried out within 24 hours, but identification will also depend on establishing an accurate record of the missing.

Forensic scientists working to establish the fire’s point of origin will use witness testimonies and a knowledge of the characteristic ways in which fire propagates.

Dr Peter Mansi, a partner at Fire Investigators UK, and previously an officer at the London Fire Brigade for 30 years, said: “The most complicated bit is establishing why the fire started. Someone has reportedly said, ‘It was my fridge,’ but no one knows that yet.”

Wilson echoed this, saying that, while witness accounts would be considered, investigators would enter the building with an open mind. “You can show 10 people one event and they all recall it differently,” she said. “You have to make your own decision about where the fire started.”

Fires tend to burn upwards and outwards in a V-shape, although the exact course and the speed with which flames and smoke propagate also depends on the structure and material of a building. Stairwells can have a chimney effect, funnelling flames upwards, while corridors can have a so-called trench effect.

Once an area of origin is pinpointed, investigators will sift through layers of ash to work out what was in the room before the fire.

“Everything that is potentially of interest goes into evidence,” said Wilson. “Everything else is preserved as well in case we get more information further down the line.”

They will be looking for fragments of electrical appliances, fuses and baubles of copper (sometime microscopic in size), that are left behind when wires melt during electrical explosions. The possibility of the fire being deliberate, or due to dangerous behaviour, such as using a barbecue indoors, will also be considered.

“We would go through all of that through minute detail down to even sieving if we need to,” said Wilson, speaking generally, rather than specifically about the Grenfell investigation. “We’re looking for anything that was originally in that area.”

Investigators will also bring in specialists in computer simulations with the aim of reconstructing the route of fire and smoke through ducts, up panelling, along corridors and through ceilings. The movement of tenants who escaped and locations of victims will be mapped too.

The mechanisms of how the fire spread and how this was possible will be interrogated. Tower blocks should be designed to restrict fires to compartments.

Andy Wade, a fire investigator at First Forensic, a firm based in Cheshire, said: “Fire doors on internal staircases should mean there is a safe exit even though the rest of the building is alight. There is a question of if that was breached.”

Wilson said the complexity of the investigation ahead meant that searching and evidence gathering would take weeks and reaching a definitive conclusion about the cause of the fire – if one is reached at all – would probably take months. “People usually expect there to be answers in a day or two. That can’t happen.”