Arrested by the Allies and convicted of war crimes in the Belsen Trial, Stärfl was executed by hanging at Hamelin prison [de] in 1945.

From October 1934 to 1935 he served in the Reichswehr, but he decided a greater opportunity to be a professional soldier was to be found in the SS, which he joined in April 1936.

[4] Near the end of the war, as the United States 9th Army approached Mittelbau-Dora, Stärfl was ordered by SS-Obersturmführer Franz Hössler to evacuate Kleinbodungen on 4 April 1945.

The next day, 610 prisoners were led outside the camp by Stärfel, his deputy Wilhelm Dörr, and 45 SS-men to the nearest town of Herzberg to be "evacuated" by rail.

[5] By 10 April 1945, after some prisoners had managed to escape, the evacuation transport came to the village of Groß Hehlen north of Celle, near the front lines.