Police investigating the 2017 Grenfell Tower fire have handed over files of evidence relating to 20 companies and 54 individuals to prosecutors.
The Metropolitan police described the move as a "milestone" moment that paved the way for what it said would be "the very best possible evidence for charging decisions".
Potential offences include corporate manslaughter, gross negligence manslaughter, health and safety offences, fraud and fraud-related offences and misconduct in public office.
The Guardian has learned that a leading prosecutor has been appointed to head any possible court cases.
The fire on 14 June 2017 – which was found by a public inquiry to have been avoidable – led to the deaths of 72 people in North Kensington, west London. It was the result of "decades of failure" by central government to stop the spread of combustible cladding combined with the "systematic dishonesty" of multimillion-pound companies whose products spread the fire, a public inquiry found in 2024.
The Crown Prosecution Service (CPS) has said charging decisions will be made before the 10th anniversary of the disaster, which falls on 14 June 2027.
Kevin Southworth, a deputy assistant commissioner at the Met, said: "This is a milestone moment in the police investigation into this devastating tragedy which took the lives of 72 people.
"We appreciate, of course, it has taken nine years to get to this point. As we have said before, this is one of the most complex investigations ever undertaken by any UK law enforcement agency – the scale is truly enormous.
"While we know this has had a significant impact on those waiting for answers, it has necessarily taken this long to ensure our investigation is meticulous and presents the very best possible evidence to the CPS for charging decisions."
Investigators have looked at the role of more than 15,000 people and 700 organisations as part of the inquiry, and have submitted 12,600 pages of evidence to the CPS.
A total of 14,700 statements have been taken and more than 27,000 exhibits, including cladding, insulation, doors, windows and other parts of the building, down to screws, nuts and bolts, are stored in a secure warehouse.
Scale replica parts of the tower are being built at a cost of £2m in anticipation of potential court proceedings.
Frank Ferguson, the head of the CPS's special crime and counter-terrorism division, said: "Today marks an important step in the Grenfell Tower investigation, and we understand the enduring impact this tragedy continues to have on bereaved families, survivors and all those affected."
He added that the CPS remained confident that it would complete the process and make charging decisions before the 10th anniversary of the fire next year.
Grenfell United, which represents some bereaved families and survivors, said: "We expect the Met and the CPS to do everything in their power to make sure this case moves forward without further unnecessary delay. Our families have waited long enough.
"We want those responsible to face justice. If people are found guilty of crimes that cost our loved ones their lives, we want to see them behind bars. Only then will people see that there are real consequences for what happened at Grenfell."
Survivors and politicians called for justice to be achieved rapidly before the 10th anniversary of the disaster.
The Labour MP for Kensington and Bayswater, Joe Powell, said: "We must do everything in our power to ensure that justice is delivered as swiftly as possible."
Sadiq Khan, the mayor of London, thanked investigators for "painstakingly" examining thousands of pieces of evidence, while the Labour MP David Lammy expressed disappointment it had taken so long.
Lammy said: "I said the morning after Grenfell that it was an act of corporate manslaughter. I'm pleased that this has happened but disappointed it has been so slow."