The Metropolitan police say they have carried out 13 interviews under criminal caution as part of their investigation into the Grenfell fire.
The potential criminal offences police are investigating range from the most serious, manslaughter, through to health and safety offences.
The new figure of interviews carried out under caution shows the criminal inquiry is progressing, albeit painfully slowly for the survivors and bereaved families.
The disaster at the west London tower block, which claimed 72 lives, shocked Britain and its second anniversary falls next week.
The Guardian understands that some of those questioned were interviewed as representatives of their organisation, and some as individuals.
Detectives have carried out two new interviews under caution since March, as they work their way through hundreds of thousands of documents and a phalanx of contractors and subcontractors at Grenfell whose work they are examining to see what part it played in the blaze and its devastating spread.
There have been no arrests and the Met has said that a decision on whether charges will be brought could be at least two years away.
They believe they need to wait for the second phase of the public inquiry to be completed. Thus, they would not submit files to prosecutors to consider charges until the second half of 2021. After that lawyers at the Crown Prosecution Service (CPS) would need additional time to consider the evidence, which is expected to be hugely complex.
Interview under caution ensures evidence is admissible in court if charges are brought, but also means the rights of a suspect are protected.
In a statement on Friday, the Met police said: “A total of 13 interviews under caution have been completed and more are scheduled. This number will continue to increase as progress is made with the investigation.”
The force would not say how many people were interviewed or whether any people had been interviewed under caution more than once.
Police still have masses of material relating to the disaster to comb through, as do prosecutors at the CPS.
Police and CPS lawyers have been in discussion about the investigation since it began, which is normal in a criminal investigation.
Survivors and those bereaved by the disaster on 14 June 2017 feel frustrated and angry in their fight for justice.
The police criminal inquiry and the public inquiry have been cooperating, but key issues remain unresolved, such as whether any criminal trial could be prejudiced by criticism in the public inquiry’s final report. The public inquiry is not supposed to apportion blame but any potential defendant could try to have a criminal charge thrown out because of potential prejudice to a fair trial.