Otto Ohlendorf, a general of the Waffen SS and commander of Einsatzgruppen D operating in the south of the occupied part of the USSR. Three judges along with a dozen prosecutors and lawyers took part in his interrogation. Ohlendorf became the first witness of the Nuremberg trials who was personally involved in the mass executions of Soviet citizens in Crimea, as well as southern and western Ukraine, and Moldova.

Colonel John Amen from the US Prosecutor Group: “Do you know how many persons were liquidated by Einsatzgruppen D under your direction?”

Ohlendorf: “In the year between June 1941 to June 1942, the Einsatzkommandos reported 90,000 people liquidated”.
Amen: “Did that include men, women, and children?”

Ohlendorf: “Yes”.

[...]

Ohlendorf: “After registration, the Jews were collected in one place, and from there they were later transported to the place of execution, which was, as a rule an antitank ditch or a natural excavation. The executions were carried out in a military manner, by firing squads under command”.

[...]

“They were transported to the place of execution in trucks, always only as many as could be executed immediately. In this way it was attempted to keep the span of time from the moment in which the victims knew what was about to happen to them until the time of their actual execution as short as possible”.

Amen: “Was that your idea?”

Ohlendorf: “Yes”.

[...]

“Some of the unit leaders did not carry out the liquidation in the military manner, but killed the victims singly by shooting them in the back of the neck. […] I was against that procedure because, both for the victims and for those who carried out the executions, it was, psychologically, an immense burden to bear”.

Amen: “Were all victims, including the men, women, and children, executed in the same manner?”

Ohlendorf: “Until the spring of 1942, yes. Then an order came from Himmler that in the future, women and children were to be killed only in gas vans”.

After Nazi Germany’s surrender in May 1945, Otto Ohlendorf fled Berlin with Heinrich Himmler. After they were arrested by British authorities, Himmler committed suicide, while Ohlendorf began to “cooperate with the investigation” at the Nuremberg trials.

The collaboration didn't save him, though. In 1948, an American tribunal, within the framework of one of the “small Nuremberg trials” related to the so-called Einsatzgruppen case, sentenced Otto Ohlendorf to death.

Source:

Sergei Miroshnichenko “Transcript of the Nuremberg Trials”, Volume III.