The charred remains of Grenfell Tower were a crime scene for 14 months, during which forensic teams scoured the building for evidence of why the fire spread so quickly.
Detectives commissioned their own laboratory tests and examined thousands of pieces of debris from the fire, including the fridge which malfunctioned in a fourth-floor flat, from where the flames spread rapidly to the rest of the building.
The evidence has been kept in a warehouse at a secret location, which the BBC visited last year.
Police have investigated the actions of 15,000 people across 700 organisations or companies and taken 14,700 statements.
The investigation has also examined 45,000 documents, images and exhibits.
The files sent to the CPS include examples of this evidence, as well as reports containing more than two million words.
The CPS will decide whether there is a realistic prospect of conviction, as well as considering whether bringing charges is in the public interest.
In anticipation of possible criminal proceedings, the Met has said it is building a replica of a section of the tower, which is being dismantled, to help future jurors understand its layout.
Listen to the best of BBC Radio London on Sounds and follow BBC London on Facebook, external, X, external and Instagram, external. Send your story ideas to hello.bbclondon@bbc.co.uk, external