“Had we killed 10.3 million Jews, then I would be satisfied and would say, ‘good, we exterminated an enemy’.” In The Devil’s Confession: The Lost Eichmann Tapes (BBC Two), an architect of the Holocaust admits everything. Here is the boastful, unvarnished voice of anti-Semitism, frankly outlining his propulsive role in the murder of millions of Jews.

The tapes in question contain many hours of interviews given in 1957 by Adolf Eichmann to Willem Sassen, a Dutch journalist with Nazi leanings. Both were exiles in Buenos Aires. Although transcripts soon emerged, the audio evidence would have been invaluable to the prosecution when, in 1961, Eichmann, denying all charges, was tried in Jerusalem. 

The tapes finally came to light when the German government granted access to two Israelis – producer Kobi Sitt and writer-director Yariv Moser. Their documentary was shown in Israel last year. This trimmed two-part version (both parts are available on iPlayer now) finds itself scheduled at a pivotal moment in Israel’s history, deepening the tapes’ significance. 

As is carefully outlined here, they have value in the ongoing fight against Holocaust denial. But at the height of the Cold War they were also geopolitical gelignite for both Israel and West Germany.

Blending scholarly heft and thriller-ish pace as it commutes across decades and continents, this is an impeccable production on every level. It reanimates the tapes in dramatised reconstructions of unusual subtlety, intercut with copious footage from the courtroom, while top-drawer historians and the trial’s surviving participants helpfully contextualise.

It so happens that my great-uncle, Julian Layton, in Vienna to extract Jews from Austria in 1938, had to deal with Eichmann. On the afternoon before Kristallnacht, Eichmann even warned him to avoid the Jewish quarter. In the dock Eichmann pretended to be an obedient nonentity, prompting Hannah Arendt’s much-quoted dictum about “the banality of evil”. The monster that Julian negotiated with is now revealed. On 67 hours of tape Eichmann rejoices bombastically in his former status as a genocidal big shot. At one point he’s heard comparing a fly, which he swats, to a Jew.

It’s as if a dam has burst. “I didn’t care about the Jews I deported to Auschwitz,” he blurted. “I didn’t even care if they were alive or already dead.” Other Nazis in the room, fearful the tapes would reach the wrong hands, couldn’t shut him up. “We can’t do this,” someone mutters as a triumphant Eichmann gaily lets the cat out of the bag.