The conclusions of the Egrant inquiry have sparked a war of words between sacked FIAU investigator Jonathan Ferris and former Pilatus Bank employee Maria Efimova.
The acrimonious exchange between the two came a day after a magisterial inquiry concluded there was no link between the secret Panama company and the prime minister's family.
Ms Efimova was behind the claims surrounding Egrant Inc, first broken on slain journalist Daphne Caruana Galizia's blog.
Mr Ferris was one of the police officers who had arrested and charged Ms Efimova with misappropriating €2,000 from Pilatus Bank and also with the defamation of her interrogators.
In an interview with LovinMalta on Monday, the former FIAU investigator accused Ms Efimova of having "invented things from A to Z" about him, including that he had induced a miscarriage.
“We were Efimova’s first victims and we are still suffering from her lies,” said Mr Ferris who was sacked by the FIAU in June 2017 in what he alleges was an attempt to silence him.
"I don't know if she was telling the truth about Egrant or not, but experience tells me to be sceptical."
The Russian national promptly posted a tweet in return, deriding Mr Ferris: "How low one can get? Crooks' doormat, you've put me through the hell, and you are trying to make even more damage. Two months ago you were ready to come to Athens to testify in my favour, remember?"
Shame on you, Jonathan Ferris. How low one can get? Crooks' doormat, you've put me through the hell, and you are trying to make even more damage. Two months ago you were ready to come to Athens to testify in my favour, remember?
— Maria Efimova (@MariaEfimova7) July 23, 2018
Ms Efimova had claimed she was mistreated during the interrogation and pressured to plead guilty.
She said Mr Ferris never appeared in court to testify in the case initiated against her. Six hearings were held between February and June 2017, all of which were postponed because of his no-show, she said.
She then moved to Greece and last April a court in Athens refused an appeal by a Greek prosecutor on the decision not to extradite her to Malta.
The exchanges came just hours after MEP David Casa published a secret FIAU document showing a connection between the Prime Minister’s chief of staff Keith Schembri and Tourism Minister Konrad Mizzi with another secret Panama company.
The FIAU responded by saying the leaked document contained "inaccuracies and omissions" and accused whoever had leaked it to Mr Casa of "criminal acts".