Mikson was born in Tartu, in Governorate of Livonia, then part of the Russian Empire. At a young age, he started playing sports, including football, basketball and ice hockey. At the age of 19, he joined the army where he served for one and a half year. In the 1930s he played football semi-professionally while also studying in the police academy in Tallinn. A multi-sport athlete, he also played basketball in Tallinn rom 1934 to 1936. He later worked for the Estonian political police (PolPol). He escaped Estonia following the Soviet invasion of Estonia in 1940 but returned during Germany's occupation of Estonia.[1]
Mikson escaped from Estonia to Sweden in 1944. In 1946, he was transported to the Norwegian border, where a boat to Venezuela waited. However, the boat was stranded in Iceland, and he remained there until his death.[2][3]
After moving to Iceland, he first lived in Akureyri. In 1949, he married Sigríður Bjarnadóttir and together they moved to Vestmannaeyjar where he became an athletic coach. Mikson has been credited as one of the pioneers of basketball in Iceland and was the first coach of ÍR men's basketball team that competed in the inaugural Icelandic Basketball Tournament in 1952.[1]
Mikson himself claimed in 1992 that he was being called a Nazi collaborator and war criminal because of a "former colleague from the Estonian police force who is now a rich man living in Venezuela and who wanted revenge after I wrote an article about him and his crimes against Estonians in World War II".[5]
In 1999, the Estonian International Commission for Investigation of Crimes Against Humanity singled out Mikson, along with Ain-Ervin Mere, Julius Ennok and Ervin Viks, for having signed numerous death warrants when they were members of the Political Police (Department B IV), headed by Ennok.[6]
In 2001, the Simon Wiesenthal Center published allegations that Mikson committed war crimes against the local Jews during the German occupation of Estonia, when he was working as Deputy Head of Police in Tallinn/Harjumaa.[7] Mikson's descendants have reportedly claimed that he had been at least on one occasion imprisoned by the Germans for hiding details about witnesses from his superiors. However, records obtained by the Simon Wiesenthal Center indicate that he was actually detained for possessing gold stolen from his Jewish victims.[7][failed verification]