A US auction house has announced it will put under the hammer the journals of Nazi war criminal Josef Mengele, the so-called "Angel of Death" who decided life or death and directed gruesome medical experiments in concentration camps. The Connecticut-based Alexander Autographs said Thursday's the auction would include some 3,500 pages of "hidden journals" of the doctor at the Auschwitz-Birkenau death camp. The items are expected to fetch between $300,000 and $400,000. The identity of the owner was not indicated.Alexander Autographs, which specializes in historical manuscripts, said the auction would include a "historically important" lot of 31 manuscripts in various forms, including bound journals.Some were written in Paraguay and Brazil, where Mengele lived after fleeing Europe at the end of World War II until his death in 1979. "All writings are penned in ink in a legible hand, in generally excellent condition," the auction house said. Mengele was a member of the Nazis' elite SS, which ran death camps across occupied Europe.The journals include some poems written by Mengele as well as commentaries on various subjects. In one, according to the auction house, he indicated that sexual promiscuity has led "to a dreadful mixing of the races with the northern Europeans... when you start mixing the races, there is a decline in civilization."Based at Auschwitz from 1943, Mengele was among those who supervised the selection of prisoners on arrival to death camps, sending those deemed unfit for slave labor to be gassed with the 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 escaped to Latin America at the end of World War II, and died in a drowning accident in Brazil in 1979.