
The 6-year-old's body was found face down in a shallow grave at Whirinaki Beach near Napier eight days after she disappeared on June 19, 1987.
In October 2002 Jules Pierre Nicolas Mikus was sentenced to life in prison and preventive detention for the historic crime.
A jury also found him guilty of raping, sexually violating, and detaining Teresa against her will.
He denied the charges but after a trial in the High Court at Wellington Mikus was convicted and jailed for life.
The trial jury heard that Mikus went to a Napier school at play-lunch time looking for a child.
He took Teresa to a remote part of Whirinaki Beach, violated her and then smothered her by putting his hand across her nose and mouth.
The New Zealand Herald can today reveal that Mikus has a terminal brain tumour.
He is currently being treated in a medical unit at Rimutaka Prison.
Two sources said he was severely unwell.
"He is in the (medical unit) and on his way out," said one source.
Corrections refused to comment on Mikus' health.
"We are legally obliged to comply with privacy legislation and the Health Information Privacy Code, which prevents us from providing personal information relating to a prisoner's healthcare," said a spokesperson.
They did explain how someone like Mikus would be treated behind bars with a terminal illness.

"All prisons provide primary healthcare services, which include general practitioner services, nursing, basic dentistry and some disability support services.
"Prison health centres do not provide hospital-level care or specialist services."
Teresa's family have been contacted for comment.
Mikus got away with murder for 15 years - but when advances in DNA enabled police to match him to samples taken at the time of Teresa's brutal killing, he was finally captured.
He had been a suspect early in the investigation but had an alibi that was not challenged.
Mikus has been denied parole several times - most recently in April 2016.
At that hearing the Parole Board made a postponement order for five years meaning they would not see Mikus again until December 2020.
At the time board panel convenor Justice Marion Frater said Mikus had consistently failed to engage with the parole process "from the beginning".
"Nor has he taken any steps to address his very serious sexual and violent offending. He has declined to participate in assessments for the Parole Board and declined to participate in any interventions with a departmental psychologist," she said.
"Given his assessed very high risk of sexual reoffending we are satisfied that even if Mr Mikus changes his mind and engages now, it will take at least five years before there is any prospect that he could safely be released.
"Accordingly, we make a postponement order of the maximum duration."
A spokesman for the Parole Board said his postponement order had not changed and no application had been made for an earlier hearing date or compassionate release.
After he was sentenced the Herald revealed Mikus had a raft of offences to his name, starting in his teens.
He was sent to prison for the first time in 1977 after he indecently assaulted a girl under 16.
Mikus also has convictions for multiple burglaries, assault with intent to rape, fraud, bigamy, escaping custody and various other driving, drug and weapons offending.
Before his arrest for Teresa's murder, his last conviction was in 1997 when be breached periodic detention and was fined $150.
Comments
To ask the family for comment is typical of the media - they're not concerned its of poor taste.
This case will go down in NZ history as changing the way we brought up our children and our gender animosities.
Sadly, all because of an isolated one off incident. As a result:
We stopped our kids go to school on their own anymore.
We created the phenomenon of "stranger danger" - which has been proved to be the worst thing taught to kids and debunked by the NZ Police (I've split the link in 2 so it can show on here so join the link together)
https://www.police.govt.nz/advice/personal-and-community-advice/school
-portal/latest-news/who-abuses-children
It created "all men are evil" syndrome.
This case stopped men walking with their daughters let alone hugging them.
This case caused parents to create in some women (now in the 30s) "social phobia" who will now not talk to males and in some cases will not work with them.
RIP Teresa & her family. And may you be left in peace.
"Corrections has a statutory obligation to ensure prisoners receive the same standard of care that they would receive in the community".
Meaning he should be on a waiting list, has to pay for his own cancer care, be told his operation has been put back another month, suffer the delays of the hospital system.












