After a marathon trial lasting five months, Sica was found guilty on Tuesday of murdering his former girlfriend Neelma Singh, 24, her brother Kunal, 18 and sister Sidhi, 12, in their suburban Brisbane family home in April 2003.
Sica claimed he only found the bodies at the house but jury accepted evidence he strangled Singh in a fit of rage, then bludgeoned Sidhi to death and drowned Kunal in a spa to avoid leaving any witnesses.
"These are brutal, horrific crimes in the worst category of murder," judge John Byrne said during sentencing. Byrne said Sica had shown no remorse, describing him as manipulative and deceitful.
Sica had lived next door to the Singhs, a Sikh family originally from Fiji, for several years and had rekindled a relationship with Neelma shortly before her death by falsely claiming he had a brain tumour and just weeks to live.