Aged 26, he penned his account of life in the infamous death camp in 1944 and only now have they been decoded now thanks to digital imaging, according to the BBC.
"Often I thought of going in with the others, to put an end to this. But always revenge prevented me doing so. I wanted and want to live, to avenge the death of Dad, Mum and my dear little sister," he wrote.
Historians say Nadjari stuffed his 13-page manuscript into a Thermos flask, which he sealed with a plastic top. He then placed the Thermos in a leather pouch and buried it.
"The crematorium is a big building with a wide chimney and 15 ovens. Under a garden there are two enormous cellars. One is where people undress and the other is the death chamber. People enter it naked and once about 3000 are inside it is locked and they are gassed. After six or seven minutes of suffering they die," he wrote.
His accounts also provide intricate details of the sickening ways the Nazi's disguised the gas chambers as showers.
"The gas canisters were always delivered in a German Red Cross vehicle with two SS men. They then dropped the gas through openings — and half an hour later our work began," he wrote.
"We dragged the bodies of those innocent women and children to the lift, which took them to the ovens."
Mystery of 36 years
According to the BBC, the notes were found by a Polish forestry student during digging at the site — 36 years after they were buried.
Russian historian Pavel Polian said only 10 per cent of the notes could be deciphered when they were first found.
The ink had faded over time and the text was virtually impossible to read.
"The inmates obviously discussed how many trains had arrived," Polian told the BBC.
"Nadjari's desire for revenge stands out — that's different from the other accounts. And he pays much more attention to his family. For example, he specifies who he wants to receive his dead sister's piano."
Nadjari's life
According to the Institute of Contemporary History in Munich, Nadjari was one of the few inmates to survive Auschwitz. He was then deported to the Mauthausen concentration camp in Austria as the Third Reich collapsed.
After the war, he married and in 1951 moved to New York. He already had a 1-year-old son, and in 1957 his wife Rosa gave birth to a girl, whom they named Nelli — after Nadjari's late sister.
In pre-war Thessaloniki he had worked as a merchant. In New York he made a living as a tailor.
Nadjari died in 1971, aged 53 — nine years before his Auschwitz message was discovered.