BLACK HAT: New Zealander Barnaby Jack, 35, was a celebrated computer hacker who forced bank ATMs to spit out cash and sparked safety improvements in medical devices.

A prominent New Zealand hacker who discovered a way to have ATM machines spit out cash and was set to deliver a talk about hacking pacemakers and other wireless implantable medical devices has died in San Francisco.

Barnaby Jack died on Thursday (local time), although the cause of death is still under investigation, San Francisco Deputy Coroner Kris Barbrich said. Craig Brophy, a spokesman for computer security firm IOActive, where Jack worked, confirmed his death and said the company would be issuing a statement.

His sister Amberleigh Jack, who lives in New Zealand, told Reuters he was 35. She declined to comment further, saying she needed time to grieve.

Jack was scheduled to speak on August 1 at the Black Hat security conference in Las Vegas. The headline of his talk was, "Implantable Medical Devices: Hacking Humans", according to a synopsis on the Black Hat conference website.

Jack planned to reveal software that used a common transmitter to scan for and "interrogate" individual medical implants, the website said.

The topic was reminiscent of the second season of the TV drama Homeland where terrorists kill the vice president by hacking into his heart device.

Jack made headlines at the conference in 2010 when he demonstrated his ability to hack stand-alone ATMs. He was able to hack them in two ways - remotely and using physical keys that come with the machines.

He had spent years tinkering with ATM machines and found that the keys that came with his machines were the same for all ATMs of that type made by that manufacturer. He used his key to unlock a compartment in the ATM, and then used a USB slot to insert a program that commanded the ATM to dump its vaults.

In the second method, he exploited weaknesses in the way ATM makers communicate with the machines over the internet.

"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 talk, but instead leave the slot open so people can commemorate his life and work.