Sperl himself and his brother were arrested by Czech guerrillas in May of 1945. Because of his participation in the Freikorps of 1938, he was sentenced to 15 years imprisonment after cruel maltreatment during the initial trial. He had to serve ten years, partly in forced labour in the coal or uranium mines.

His mother, his brother who had been released in 1946, and his sister were expelled in 1946 and re-settled in Legau, a village in Southern Germany. Mizzl and her widowed mother remained in Eisenstein and until 1948 and then moved to Legau, too.

Lothar Sperl was able to paint even as a prisoner; as early as 1945, he decorated the ceiling of the prison chapel. In 1952 he wrote home: “I am alright on the whole, I am treated well, I paint, I sculpt, and I find consolation in my work..”

In December 1955 He was finally released and moved to Legau to be with his wife.

The local administration presented him with his first set of painting equipment in the Federal Republic and he began work with great energy. It was, after all, a question of establishing himself anew and earning a livelihood for himself and his wife. With the help of his brother-in-law, who had returned to his home town of Traunstein in Bavaria, the Sperls were able to purchase a house in the newly founded town of Traunreut nearby and build a studio for Lothar.

Two kinds of commissions which he gained at that time made this financially possible. On the one hand, through the intermediary of his cousin Weinberger in Vienna, he was commissioned to paint portraits of the Austrian cabinet, which introduced him to Viennese society and brought further work.

On the other hand, he specialised in fresco-painting and sgrafitto. His first project was to decorate the front of the new town hall of Traunreut.