The Crown's case was largely circumstantial and was based on the impending probability Aaron was becoming aware of his father's dishonesty.
Last year in July, Riogard's case was heard in the Court of Appeal by Justices French, Cooper and Clifford.
The judgement, which was released today, outlined four grounds of appeal put forward by Roigard's lawyer, Robert Lithgow QC.
"Both had significant histories of dishonesty and their dishonesty was underlined in cross-examination," the report said.
One witness was said to have reported Roigard told him he had struck his son three times from behind, using a wood splitter as a weapon, then he disposed the body.
The other inmate who gave evidence said Roigard told him the police would never find his son's body and "he got what he deserved".
Lithgow argued allowing the use of inmate confession evidence meant the courts were "directly procuring, rewarding and enforcing the evidence of fraudsters, for payment".
The fact the evidence was "paid" - in terms of the rewards offered and provided for giving it - should be enough to exclude it, he said.
"Where a case involves allegations of murder and there is no body, the inmate can fabricate a story with little chance of being caught out," Lithgow argued.
In the appeal judgement, Judge Cooper said he was unable to accept the ground of
appeal, "because it is contrary to the Supreme Court's decision" in Hudson - another High Court ruling.
Another ground of appeal alleged that trial counsel, Mr Keegan, allegedly destroyed the foundation of the defence he was instructed to present.
Judge Cooper said, "In reality that is simply a reworking of the first ground of appeal, claiming that the evidence is generically bad because of the character of the witnesses".
The fourth ground of appeal focused on evidence called by the Crown about
internet material accessed by Roigard concerning a "Mexican chainsaw massacre" and how a blow to the head could result in instant death.
He claims that this evidence was all prejudicial, but of no probative value and should not have been admitted.
In relation to the sentence appeal, it was claimed that the case did not meet the
criteria for the imposition of a minimum non-parole period.
However, the Court of Appeal judges deemed a combination of factors involved in the case were adequate to impose the minimum term of 19 years.
"We are satisfied that the combination of circumstances on which the Judge relied was sufficient for the imposition of the minimum term of 19 years," the report said.
"The appeal against sentence is dismissed accordingly. The appeals against conviction and sentence are dismissed."