He was tossed out of school in 1933 at the age of 13 because he was Jewish, but managed to finish his high school education in another city under an alias in 1938 with a qualification in precision engineering.
Jaku said his qualification spared him the gas chambers in the years that followed because he worked as a slave laborer.
He was sent to and escaped from concentration camps including Buchenwald and Auschwitz, where his parents were gassed on arrival.
He escaped from what he suspected was a death march as an Auschwitz prisoner as Allies approached. He spent months in hiding before U.S. troops found him near starved and sick with cholera and typhoid.
In 1946, he married in Belgium his Jewish wife Flore, who had spent a comparatively uneventful war in Paris pretending to be Christian, and they migrated to Australia in 1950.
The husband worked at a Sydney garage and his wife as a dressmaker before they went into real estate together.
Forever marked with an Auschwitz prisoner number tattooed on his left arm, he also became a volunteer at the Sydney Jewish Museum, sharing his experiences and philosophies of life with visitors.