In 1943 ReichsführerHeinrich Himmler appointed SS judge Dr. Georg Konrad Morgen to investigate charges of cruelty and corruption at the Buchenwald camp. Due to his excessive brutality and sadism, Sommer was indicted and tried before Morgen. Commandant Karl Koch and his wife Ilse Koch were also put on trial. According to Morgen, Sommer had a secret compartment underneath the floor under his desk. He kept his private instruments of torture concealed within this compartment such as the needles he used to kill his victims after he was done torturing them, he would inject them with carbolic acid, or inject air into their veins causing their death by embolism. On occasions, after private late night torture sessions Sommer would hide his victim's bodies under his bed until he could dispose of them in the morning. Among his acts of depravity were beating a German pastor, hanging him naked outside in the winter then throwing buckets of water on him and letting him freeze to death. On another occasion Sommer beat a Catholic priest to death for performing the Sacrament of Penance for a fellow inmate. After the SS trial Sommer received a reduction in rank and was sentenced to a penal battalion fighting on the Eastern Front where he was wounded in a tank explosion, losing his left arm and right leg. He was taken captive by the Red Army and was detained as P.O.W. until 1950 when his prisoner status was upgraded to war criminal. He was released from Soviet captivity in 1955 as part of the negotiations conducted on behalf of Soviet held German prisoners by Konrad Adenauer.
Retrial and imprisonment
After his release he returned to West Germany where he married, fathered a child and filed for and received a pension for his service related disabilities. He escaped punishment for his crimes until 1957, when he was indicted for complicity in the death in 101 concentration camp inmates. In July 1958 in Bayreuthdistrict court in West Germany, he was ultimately convicted of 25 deaths and received a life sentence. Upon appeal, the case was upheld in May 1959 by the Federal Court. Sommer spent the rest of his life behind bars. He died in the prison hospital in 1988.