Sean Davison received a joyous and warm welcome back into the country after he landed at Cape Town International Airport on Wednesday, the broadcaster reported.
He wrote a book called "Before We Say Goodbye", published in 2009, in which he wrote 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.
His wife and two children were among those awaiting his arrival at the airport, the SABC reported.
Davison headed the forensic DNA analysis laboratory at the University of the Western Cape, where he was expected to return.