Kiwi euthanasia is now facing a second charge of murdering a disabled person.
According to BBC, Sean Davison appeared at the Magistrate's Court in Cape Town on Friday on two counts of murder. Charges he denies.
The 75-year-old identification scientist founded the Dignitas organization.
Davison is now charged with killing Justin Varian by placing a bag on his head and managing helium BBC reports.
Varian died on July 25, 2015. He was diagnosed with motor neuron disease a few years earlier.
Davison has already been charged for the death of a friend, Enrique Burger, 43, on November 2, 2013.
Burger became half-something after a car accident.
Oakland native Davison moved to South Africa in the early 1990s and continued to be a professor of biotechnology at the University of Western Cape.
Davison won the headlines in New Zealand when he was convicted of the death of his 85-year-old mother, who suffered from terminal cancer.
Archbishop Desmond Tutu wrote to the judge and asked for leniency, and gave Davison a reference to the character BBC reports.
Davison served five months in house arrest after pleading guilty to his mother's suicide before returning to South Africa in 2012.
He is now on bail, and is scheduled to appear again in court on January 29.
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