Western Cape university professor Sean Davison said he would not speak again about his mother's death, as it was time to move on.
“I don't feel I need to talk about it again. The issue is finished and now we're looking ahead,” he told reporters at the University of the Western Cape (UWC) on Friday.
He said his focus would be on encouraging the debate around legalising euthanasia in South Africa, as the country had already led debates on abortion and HIV/Aids.
He launched a petition on Dignity SA's website on Thursday, calling for a euthanasia bill to be brought before Parliament.
Davison said he was drafting the bill with an unnamed MP.
The UWC would also hold a series of talks in which people of opposing views could debate the issue.
UWC Rector and Vice-Chancellor Brian O'Connell welcomed Davison back to the university as head of the forensic DNA laboratory.
“Had I been in Mr Davison's shoes, I would have done the same thing,” he said.
The professor returned to South Africa on Wednesday after serving a five-month detention.
He wrote a book called “Before We Say Goodbye”, published in 2009, in which he stated that when he returned to New Zealand to look after his cancer-stricken mother, she asked him to help her die.
She had gone on a hunger strike to try to end her life. He crushed several morphine tablets and mixed the powder with water, which she drank.
Davison pleaded guilty in the Dunedin High Court last year to a lesser charge of inciting and procuring his mother to commit suicide. He was originally charged with attempted murder and was arrested in September 2010.
Davison said his mom had enjoyed a colourful life and travelled the world before she fell ill.
“In the end, she was an elderly lady waiting to die,” he said.
“It got the point where she couldn't take her own life. She wasn't the type of person to ask for help... (but she did ask for help) and after some very deep thought I helped her.”
He said he did not think at any point that his actions would lead to an arrest.
Davison spoke for the first time about a closed-door session that took place after four days of being on trial, between the State and his lawyer.
He said the two argued back and forth about details surrounding the last hour of his mom's life, dissecting the meaning of every piece of conversation that took place.
Davison told them that his final words to his mom was “to advise her again that it would end her life”.
She replied by saying: “You're a wonderful son.”
The professor maintained his innocence throughout.
“I did not commit a crime and throughout (all) this time I've stood my ground.”
Davison announced a groundbreaking rape kit he was working on with another professor.
The kit isolated Y-chromosomes in crime scene samples and could accurately identify one or multiple perpetrators. – Sapa