She is believed to have spent her childhood in Hamburg, Germany. In 1944, she became an Aufseherin in the Stutthof SK-III women's camp, where she brutalized prisoners, some to death. She also selected women and children for the gas chambers. She was so severe the women prisoners nicknamed her the Beautiful Specter.
Barkmann fled Stutthof as the Soviets approached. She was arrested in May 1945 while trying to leave a train station in Gdańsk. She became a defendant in the Stutthof Trial, where she and other defendants were convicted for their crimes at the camp. She is said to have giggled through the trial, flirted with her prison guards and was apparently seen arranging her hair while hearing testimony. She was found guilty, after which she declared, "Life is indeed a pleasure, and pleasures are usually short."