Shortly before being handed the life sentence, O'Dempsey, now 78, broke his silence claiming he was innocent of the crimes.
'I never had the slightest reason to harm the three McCulkins in any way,' O'Dempsey said.
But Justice Peter Applegarth said he was 'completely unconvinced' by the protest of innocence.
When Dubois, also sentenced to life, asked to address the court he was told by the judge to 'shut up'.
'The last hours of the lives of these three defenceless women must have been terrifying,' Justice Applegarth said.
'(Dubois) like a coward did what you were told and raped the other girl. (O'Dempsey) you are beyond redemption.'
The bodies of Mrs McCulkin and her two daughters have never been found.