Four former sub-postmistresses from Northern Ireland are at the Post Office Inquiry in London on Friday.
They are hearing evidence from a former investigator who was involved in their cases.
The four women were all affected by the Horizon IT scandal, which the inquiry is examining.
Ex-Post Office employee Suzanne Winter is set to face questions about the criminal investigation of one of the victims, Maureen McKelvey from Omagh.
Ms McKelvey was prosecuted but subsequently found not guilty after she experienced shortfalls of £30,000.
The proceedings can be watched here.
Ms Winter was also involved in the cases of the three other former sub-postmistresses attending the inquiry – Deirdre Connolly, Heather Earley and Katherine McAlerney.
More than 900 sub-postmasters and postmistresses were prosecuted for stealing money because of incorrect information provided by a computer system called Horizon.
The Post Office itself brought many of the cases to court and, between 1999 and 2015, it prosecuted 736 people – an average of one person a week.
Another 283 cases were brought by other bodies, including the Crown Prosecution Service.
Many maintained their innocence and said they had repeatedly reported problems with the software.
Some of those convicted went to prison for false accounting and theft and many were financially ruined.