Moroccan authorities have arrested three fugitive suspects in the grisly murder of two Scandinavian hikers after an intensive manhunt, a source close to the investigation said on Thursday. The arrests in the city of Marrakesh follow a first arrest on Monday, hours after the discovery of the two women's bodies in the High Atlas mountains. The man already in custody is suspected of belonging to an Islamic extremist group. Danish citizen Louisa Vesterager Jespersen, 24, and 28-year-old Maren Ueland from Norway were on a month-long holiday, Ueland's mother told Norwegian broadcaster NRK. Their bodies were found on Monday, after they had pitched their tent at an isolated mountain site two hours walk from the tourist village of Imlil. Investigators had on Wednesday night released profiles of the three fugitives. All three come from Marrakesh, and one of them had "a court record linked to terrorist acts", police spokesman Boubker Sabik said. In one of the black and white photos circulated by the authorities, one of the suspects wears long white clothing and a white skullcap, and has a long beard. A second suspect also has a long beard, while the third has a thin face and a goatee beard. "The arrests highlight the efficacity of the security forces", a source close to the investigation told AFP. The two women were attacked with a knife, according to authorities. One was then beheaded, a source close to the investigation has said. Authorities are still determining the authenticity of a grisly video posted on social media allegedly showing the murder of one of the women, the investigation source said.