Only three escapees of The Great Escape, immortalised by the 1963 Hollywood movie starring Steve McQueen, safely made it to England.
Acting on direct orders from a furious Adolf Hitler, 50 of the escaped men were murdered, including Christensen and two fellow Kiwis, Flying Officer Porokoru Patapu (Johnny) Pohe and Squadron Leader John Williams DFC (Distinguished Flying Cross).
A new book by English author Simon Read tells the story of the remarkable manhunt by a detective-sergeant from Blackpool after the war to track down the merciless killers.
Frank McKenna, a member of the Special Investigation Branch (SIB) of the RAF Police dubbed 'Sherlock Holmes', criss-crossed post-war Europe with Wing Commander Wilfred 'Freddie' Bowes on their impassioned crusade.
"Each murder case proved to have its own challenges, as they pursued every clue in the search for justice," Mr Read writes in a Daily Mail serialisation of his book, 'Human Game: Hunting the Great Escape Murderers'.
By May 1947, they had tracked down 329 suspects - 23 of whom were directly complicit in the Great Escape killings.
And soon afterwards, they trapped the man responsible for slaying Christensen.
The commandant of the holding facility in Minden called McKenna to say that the North West Europe War Crimes Unit had just brought in a man working as a haulage contractor.
"The man's name was Johannes Pohlmann, but he had been identified by a witness as former Gestapo officer Johannes Post. McKenna went to see the prisoner, and pulled from his tunic a picture of Post," Mr Read writes.
"The face was thinner - but the eyes and prominent chin left no doubt in his mind."
His cover blown, the "arrogant and sneering" Post freely admitted to knowing all about the murders of Christensen and his three mates.
He even admitted that the last word the Australian Catanach had uttered was, 'Why?'
Post and 17 others went on trial at the British Military Court in Hamburg in July 1947 charged with committing war crimes by killing and ordering to kill POWs who had escaped from Stalag Luft III.
All the defendants in what was known as the 'Sagan case' denied the charges, but were all found guilty.
Post and 13 others were sentenced to hang.
"Six months later, on gallows built by the British Army's Royal Engineers, the 14 Sagan murderers went to their deaths at the end of a rope, bringing to an end one of the most extraordinary manhunts of the 20th century," writes Mr Read.
The ashes of the three New Zealanders, along with the other 47 murdered men, are interred at Poznan Old Garrison Cemetery in Poland, the former site of Stalag Luft III which they escaped.
