Rasmussen was alleged to have produced psychokinetic phenomena, such as moving pendulums in sealed glass cases. She was endorsed as genuine by the psychical researcher Harry Price. Christian Winther (1873-1968) of the Danish Society for Psychical Research investigated her mediumship, producing a favourable report in 1930. The report was later disputed as new experiments from researchers at the University of Copenhagen in 1945 suggested all her phenomena could be explained by physical causes. In 1950, Rasmussen was exposed as a fraud as a secret camera had caught her using fraudulent methods to produce spiritualist phenomena. The exposure made headlines in Danish newspapers, seriously damaging the spiritualist community in Denmark.
- Kragh, Jesper Vaczy. Danish Spiritualism, 1853-2012. In Christopher M. Moreman. The Spiritualist Movement: Speaking with the Dead in America and Around the World. Volume 1: American Origins and Global Proliferation. Praeger. pp. 77-78. ISBN 978-0-313-39947-3
- Anderson, Rodger. (2006). Psychics, Sensitives and Somnambules: A Biographical Dictionary with Bibliographies. McFarland. p. 118. ISBN 0-7864-2770-1
- Tabori, Paul. (1966). Harry Price: The Biography of a Ghosthunter. Living Books. p. 219 (Republished in 1974 by Sphere Books) ISBN 0-7221-8326-7
- "The Rise & Fall of the Third Society" SkepticReport.