At Robertson's High Court trial, he denied intending to kill Mrs Gotingco, saying the injuries she sustained when struck by his car were accidental. He claimed to be acting without murderous intent at the time he stabbed her because she was already dead.
Robertson also denied the rape, saying evidence had been planted by police.
When it got to appeal, Robertson kept the same objections - and also claimed he was so wasted on drugs it was impossible to have an intent to murder and that Mrs Gotingco was possibly dead before being stabbed.
The shocking consequence of the latter claim was Robertson's assertion that no rape could have happened because if it did, then Mrs Gotingco had already died and a rape victim had to be living.
It was a string of claims which held no water with the Court of Appeal judges.
The evidence against Robertson was overwhelming - there was GPS evidence from an anklet he was compelled to wear after release from prison on earlier, serious offending. Robertson's high risk profile meant he was being monitored.
The GPS tracker traced Robertson from the point where Mrs Gotingco was struck, back to Robertson's house where her blood was found and then to the reserve where her body was dumped wrapped in a sheet from her killer's house. The combination of DNA and GPS evidence was damning - as was the discovery of a fileting knife in his kitchen drawer with Mrs Gotingco's blood on it.
The Court of Appeal judgment set out the string of efforts by Robertson to challenge the conviction, including: "If she was dead Mr Robertson could not have raped her and the possibility is said to arise that he lacked murderous intent because the car injuries were accidental."
He also turned to his claimed drug abuse as a factor which was overlooked, saying it should have been considered whether "drugs explain an irrational decision to mutilate what he believed to be a dead body to disguise the car injuries". It also needed to be considered "whether he believed Mrs Gotingco to be dead when he stabbed and allegedly raped her".
Mr Robertson's claims were not accepted by the judges, along with claims he made of evidence being planted and objections he raised over the use of the GPS evidence.
They also dismissed his assertion somebody else had stabbed Mrs Gotingco in the back, calling it an "inherently improbable claim".
When it came to sentencing, Robertson did have success in challenging claims he had deliberately run down Mrs Gotingco, with the judges saying they were "not satisfied beyond reasonable doubt that the running down was deliberate".
While they were "prepared to accept that the car injuries that incapacitated her were accidental", the crime remained "exceptionally cruel and brutal".
"Although it may not have been planned, the murder was calculated; he sought to escape detection by murdering Mrs Gotingco and hiding her body. He committed rape as well as murder, and Mrs Gotingco suffered greatly."
The judges said the trial Judge was correct in his assessment that it was likely Robertson would commit yet another serious offence if ever to return to society, no matter how long he was in prison.
"Mr Robertson is very dangerous to females of all ages and likely to remain so."
For this, and other reasons, the sentence of a minimum 24 years in prison - and preventative detention - were reasonable.
Robertson had previously appeal his 2006 conviction for the abduction and indecent assault on a child to the Supreme Court. He has never admitted responsibility for any of the serious crime for which he has been convicted.
