Robertson is also a child sex offender and had just been released under the strictest possible conditions - including 10 years of GPS surveillance - when he killed Ms Gotingco.
He was just 18 when he kidnapped and molested a 5-year-old girl in Tauranga in 2005.
Robertson was jailed in October 2006 for eight years after being found guilty of seven charges, including indecently assaulting the girl and attempting to abduct two other children.
On his release from prison in December 2013, he breached his conditions twice in a few weeks and was deemed such a lasting danger that he was to be monitored strictly for a decade, the maximum period of an "extended supervision order".
Robertson raped and murdered Mrs Gotingco three months after the supervision order was imposed but yet to be enforced.
Ms Adams said the case showed that "nothing is fool-proof" when it came to options for monitoring of offenders.
"None of them are silver bullets. This issue of GPS monitoring of offenders comes up often in the family violence space which I am interested in, and I think what it highlights that while it is a tool, it isn't the magic solution that some put it up to be.
"We are clearly disappointed that this murder took place...whether that demonstrates an underlying issue with the way that supervision is carried out is something we will be looking into."
Corrections Minister Sam Lotu-Iiga said the GPS monitoring had worked.
"He broke free of that, sadly, but the GPS monitoring helped ultimately locate him and help with the prosecution.
"It [the monitoring] is supposed to help stop offending. Clearly it shows where the location is, but it doesn't tell you what they are doing. I am as saddened, as most New Zealanders are, about what happened to the Gotingco family, and my condolences go to them."
Mr Lotu-Iiga said he was confident that his department had done all it could do in the case.
"You've got to remember we also passed the public protection orders and [modified] extended supervision order provisions last December, in which people like Robertson could be captured by a public protection order which would put him certainly in custody, in terms of an order. But sadly that was passed last December after this sad tragedy."
The new law passed in December gave prison authorities more power to keep dangerous inmates away from the public.
Corrections can now apply for Public Protection Orders (PPO) from the court for offenders with histories of serious violence or sexual offending.
The orders allow Corrections to keep an inmate who has served his or her full sentence in a secure area on prison grounds, and will apply in situations where measures such as parole conditions and extended supervision orders do not go far enough.
The December changes also allowed extended supervision orders to be more widely used.
Corrections had already successfully applied in February for an extended supervision order for Robertson, requiring him to wear a GPS tracker for 10 years, among other conditions.
