Max Sica was convicted by a Brisbane Supreme Court jury which found him guilty in the longest murder trial in Queensland's history.
Sica had denied killing Neelma Singh, 24, Kunal Singh, 18, and Sidhi Singh, 12, and dumping their bodies in the spa of their home in the outer Brisbane suburb of Bridgeman Downs. He claimed he found the bodies on April 21, 2003, and has maintained the deaths were caused by someone else prior to his arrival.
Sica, wearing a suit and tie, stared straight ahead and showed no emotion as the verdicts were read out, the AAP news agency reported.
Asked by the judge whether he had anything to say, he replied, “I didn't kill no one and the Queensland justice system is corrupt, and that's all I've really got to say. “Sorry about that.”
Sica is expected to receive a mandatory sentence of life imprisonment for each murder, but it is also expected the Crown will ask he serve a minimum of 45 years in jail, 15 years for each death.
Murder carries a mandatory life sentence in Queensland, with a minimum non-parole period of 20 years for those found guilty of multiple killings.
The siblings' mother Shirley Singh watched the verdict on a live video feed in another room of the courthouse. Asked what was going through her mind when the verdict was read, she said, “Horrible visions come through your head,” before being escorted away by police.
Sica's mother Anna spoke outside the court, protesting her son's innocence in an emotional outburst in Italian and broken English.
“I know my son ... my son is innocent,” she told reporters before being dragged away by her husband Carlos. Police Assistant Commissioner Mike Condon paid tribute to the hundreds of officers who had worked on the “long and very complex” eight-year investigation.
Earlier in the Supreme Court, Justice John Byrne congratulated police on their investigation. He adjourned the matter for sentencing on Thursday.
During the 77-day trial, the court heard allegations about a complicated web of relationships involving Max Sica and the Singh family.
Prosecutor Michael Byrne said after Neelma Singh and Sica had a relationship in 2002, Neelma had wanted to break it off.
However, in the weeks before her death Neelma had willingly seen Sica after he falsely claimed he had a brain tumour and just weeks to live in order to gain her sympathy.
The Crown said the three siblings were murdered at some time between April 20 and April 21, 2003. Sica went to the Singh home late on the night of April 20, 2003, to talk with Neelma and possibly have a prayer meeting about his tumour.
The Crown alleged that for some reason, perhaps out of jealously or rejection, Sica strangled Neelma in a fit of rage.
It was alleged Sica attacked Kunal and Sidhi with a garden fork because they could identify him as Neelma's killer.
Twelve-year-old Sidhi was beaten to death, most likely in her bed. Kunal, who was also most likely in his bed, was knocked unconscious.
The bodies of Neelma and Sidhi were dumped in a running spa and Kunal was also placed in the spa where he drowned.