Beheaded bodies of Louisa Vesterager Jespersen, 24, from Denmark, and Maren Ueland, 28, from Norway, were found on Monday near the mountain of Toubkal, which is the highest mountain in Morocco. Four people linked to the incident have been already detained.
Nine more people were detained in the cities of Marrakesh, Essaouira, Sidi Bennour and Tangier on Friday, the MAP news agency reported citing the Moroccan Central Bureau of Judicial Investigation.
Before detentions, the suspects issued a video pledging allegiance to the Daesh terror group. The authenticity of the video was partly proved by the Public Prosecutor General.
WATCH: Alleged VIDEO of Scandinavian Women's Killers Swearing Daesh Oath Emerges
Daesh, also known as ISIS/IS/Islamic State, is a terrorist organisation outlawed in Russia and many other countries.