In 1934–1935, he presided over the Military Tribunal trial of Neumann–Sass that involved 122 defendants accused of anti-Lithuanian activities.

After the promotion to podporuchik in July 1917, Leonas was transferred to the 2nd Battalion of the Russian Railway Troops.

[1] Leonas returned to Lithuania in 1919 and was mobilized on 1 July 1919 into the Lithuanian Army and assigned to the 8th Infantry Regiment.

He saw action in the Lithuanian Wars of Independence against Soviet Russia (July 1919 – January 1920) and Poland (August–November 1920).

[1] In February 1920, he helped to subdue a revolt by Lithuanian soldiers in Kaunas and was promoted to captain.

The case involved 122 defendants – Nazi sympathizers that were accused of various anti-Lithuanian activities in the Klaipėda Region.

[1] After the Soviet occupation of Lithuania in June 1940, Leonas was arrested on 11 July 1940 and imprisoned in Kaunas and later Lubyanka Prison.