Simon Busuttil testified before a magistrate this morning about evidence he had presented to back claims of suspicious financial transactions of some €650,000 between the prime minister's chief of staff, Keith Schembri, and Adrian Hillman, former managing director of Allied Newspapers.
Last week the Nationalist Party leader said the transactions led to suspicions of money laundering.
Dr Busuttil had originally presented documents about the transactions to Magistrate Aaron Bugeja, who said they merited a separate investigation by another magistrate.
Magistrate Josette Demicoli was chosen by secret ballot.
Mr Schembri and Mr Hillman are denying wrongdoing.
In a statement after his court appearance, Dr Busuttil said there was never any justifiable reason why Mr Schembri should have been making any payments to Mr Hillman.
"This morning I also once again confirmed under oath what I had already told Magistrate Aaron Bugeja," Dr Busuttil said.
"I have no doubt that the magistrate's conclusions, at face value, will be that criminal action should be taken against these people," he said.