Police officials probing the Post Office Horizon IT scam are now considering corporate murder charges.
In an update shared with the victims over the past few days, the National Police Chiefs Council (NPCC) said the investigation was currently focused on eight suspects, with five being interviewed under caution.
It said there are now 53 persons of interest, the majority of whom may be listed as suspects at a later stage of the investigation.
The NPCC said the investigation is focused on the crimes of perjury and perverting the course of justice, but it is also considering charges of corporate manslaughter. Companies rather than individuals face such charges.
The Horizon IT system, which began operating in 1999, created an unfair shortage of post office branches for which sub-postmasters were held accountable.
The scandal has been called the most widespread miscarriage of justice in Britain.
More than 900 people were prosecuted and some went to jail. Some people died while waiting for justice.
The criminal investigation into the scam, Operation Olympos, began in 2020. A year ago, a team of about 100 officers was launched in four regional centres, increasing its activity after the end of the public phase of the investigation into the scam.
Officials are now appealing for any former sub-postmasters who may have signed a non-disclosure agreement (NDA) with the Post Office to come forward, as it has been confirmed that the NDA will no longer be enforced.
The NPCC said: “The primary and sole focus remains on the crimes of perverting the course of justice and perjury and there has been no change.
“However, as was previously done with fraud offences, advice is being sought from the CPS in relation to corporate and grossly negligent manslaughter offences.”
The chair of the public inquiry, Sir Wayne Williams, published the first part of his final report on 8 July and the second volume is expected next year.
The police officer leading the investigation previously told the BBC that no criminal prosecution could be brought before 2028.
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