Burger had become a quadriplegic after a car accident.
Auckland-born Davison moved to South Africa in the early 1990s and went on to become a professor of biotechnology at the University of the Western Cape.
Davison previously made headlines in New Zealand when he was convicted in relation to the death of his 85-year-old mother, who had terminal cancer.
Archbishop Desmond Tutu wrote to the judge asking for leniency, and gave Davison a character reference, the BBC reports.
Davison served five months' of home detention after pleading guilty to assisting his mother's suicide, before he returned to South Africa in 2012.
He is currently on bail, and is due to appear again in court on January 29.
If you are worried about your or someone else's mental health, the best place to get help is your GP or local mental health provider. However, if you or someone else is in danger or endangering others, call police immediately on 111.
