Four suspects have so far been identified by police investigating possible criminal charges in the Post Office scandal, Sky News has learned.
Sources said among the offenses being considered are perverting the course of justice and perjury.
Hundreds of deputy postmasters were wrongly prosecuted for stealing from their branches between 1999 and 2015 after faulty Horizon software caused accounting errors.
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The Metropolitan Police is what is known as a lead participant in the Post Office’s public inquiry and has monitored and assessed the documents submitted.
The number of suspects under police investigation is expected to increase over the next six to 12 months.
More than a million documents are believed to be being examined and the number of police officers investigating the scandal has also increased from 80 to 100, with work across all police forces.
However, it is not expected that charges will be laid before 2027/28, and this deadline could be extended.
A Sky News source said the number of suspects was apparently “just a starting point”.
A meeting took place this weekend between more than 150 deputy postmasters, including Sir Alan Bates, and the Metropolitan Police.
Sir Alan said he had been told by officers that “it was going to take a few years” and that there were “no restrictions on the scale of the investigations”.
He also said the sub-postmasters’ priority was financial redress and then victims would “look for people to be held accountable.”
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A Metropolitan Police spokesperson said: “Yesterday (November 17) we met with Alan Bates and some of the relevant subpostmasters to provide an update on our progress and next steps.
“Our investigation team, made up of around 100 officers from armed forces across the UK, is now in place and we will share more details in due course.
“Initially, four suspects have been identified and we anticipate that number will increase as the investigation progresses.”