Barnaby Jack, the Kiwi hacker famous for "jackpotting" ATMs, has been found dead at an apartment in San Francisco aged 35.
The New Zealand-born hacker was found on Thursday evening by "a loved one". Police, who have not said what caused his death, have ruled out foul play.
Jack's sister Amberleigh Jack, who lives in New Zealand, thanked fans for their support, tweeting the following messages:
"So humbled by the social media flood of people that loved @barnaby_jack. thank you all so much for your kind words.
"I was always so proud. Seems I'm not the only one.
"Sorry but I need a few days to grieve with family and friends. A brief statement will be released."
The celebrated hacker's death comes a week before he was due to present his methods at a Black Hat convention in Las Vegas next Thursday.
"Barnaby had the ability to take complex technology and intricate research and make it tangible and accessible for everyone to learn and grow from," Black Hat said in a statement.
The conference said it will not replace Jack's presentation, instead leaving the time slot open to commemoration from fans.
It was at the Black Hat security conference in 2010 when Jack received global acclaim for his techniques, breaching two ATMs which made them dispense cash live on stage.
But Jack's skills in exploiting medical devices also gained him credit, such as the exploitation of various medical devices, including pacemakers and insulin pumps.
At the time of his death, Jack was the Director of Embedded Device Security at IOActive, a computer security firm with headquarters in Seattle and London.