His older brother, Kristian Aubert (1909-1942), was also an active member of the resistance during the war but was captured by the Gestapo and died from torture in 1942.
[citation needed] Aubert soon became one of the key members of the sabotage group Oslogjengen, which was under the command of Gunnar Sønsteby.
Due to his leadership skills, he was often chosen to perform the most demanding missions carried out by the group.
In early May 1945 Aubert among other members of Oslogjengen secured the archives in the Department of Justice, which revealed the actions the Nazis in Norway during the war.
When the Norwegian royal family returned to Norway after the war, Aubert served as a bodyguard.