The diaries of Nazi war criminal Josef Mengele, the so-called "Angel of Death" who tortured prisoners at Auschwitz death camp, were bought on Thursday by an Orthodox Jew for almost $A280,000.
Connecticut-based Alexander Autographs, which organised the auction, said the journals were sold to a private collector who is planning to open a museum.
The diaries, written after World War II once Mengele had fled from the Allies' clutches to Latin America, contain his philosophical reflections, autobiographical stories and poems penned between 1960 to 1975.
They include some 3,500 pages of "hidden journals" written by the doctor who carried out gruesome medical experiments on inmates at Auschwitz-Birkenau concentration camp.
The final sale price for the items, mostly small, spiral-bound notebooks, was $292,775, the vice president of Alexander Autographs, Peter Klarnet, told AFP.
"The gentleman is an individual collector from the Midwest, an orthodox Jew who is planning on opening his own museum," Klarnet said.
"He is very pleased that the diaries are now in the proper hands."
Alexander Autographs, which specialises in historical manuscripts, said the auction would include a "historically important" lot of 31 manuscripts in various forms, including bound journals.
There are also school textbooks bearing the words in Spanish "Cuaderno," or "Cultura General" or "Agenda classica" on the cover.
The contents are penned in blue ink, in a sloped, regular handwriting. Crayon drawings cover some of the pages.
Some were written in Paraguay and Brazil, where Mengele lived after fleeing Europe. He died in a drowning accident in Brazil in 1979 at the age of 67.
Alexander Historical Auctions chairman Bill Panagopulos told AFP that the seller was "an American corporation" but did not reveal its full identity.
He said the diaries had been seized in 2004 by police at the home of a German couple with whom Mengele had lived in Sao Paulo.
They were then given to Mengele's son, Rolf Mengele, who only saw his father twice in his life.
Based at Auschwitz from 1943, Mengele helped supervise the selection of prisoners on arrival to death camps, sending those deemed unfit for slave labor to be gassed with deadly Zyklon B.
He gained his notorious reputation due to his pseudo-medical experiments, for example on twins he plucked from among the prisoners.
Mengele was a member of the Nazis' elite SS, which ran death camps across occupied Europe.
After reaching Argentina at the start of the 1950s, he fled to Paraguay in 1961 still hunted by Interpol and then to Brazil, where he lived in Sao Paulo.
His death was only confirmed in 1985, after his body was exhumed.
