RNZ reports the former MPs were among the 14 sentenced to prison last year on corruption and bribery charges.
The charges came after the MPs were pardoned of the offences by the speaker of parliament, Marcelino Pepite, in his role as acting president.
The first prosecution' witness to appear was lawyer, Eric Molbaleh, who is alleged to have drafted the legal instrument that Mr Pepite relied on.
The Prosecution said there were five lawyers suspected of involvement in the conspiracy case, but they had now become state witnesses.