Moroccan authorities have four men in custody after finding the brutalized bodies of Louisa Vesterager Jespersen of Denmark and Norwegian citizen Maren Ueland. Police have linked the four to ISIS and consider the dual murders of the two young women a terrorist act. A video reportedly made of the killings, including the beheading of one of the tourists, has been authenticated by Norwegian investigators.

CBS provided the update on the authentication this morning, along with the content — in which the murderers pledged allegiance to ISIS:

4 men with alleged ties to ISIS are in custody in Morocco after the killing of two European tourists. The 2 female victims were university students from Denmark & Norway. Their bodies with stab wounds were discovered in the mountains south of Marrakesh. @HollyMAWilliams reports: pic.twitter.com/FqjLcspKCn

— CBS This Morning (@CBSThisMorning) December 21, 2018

A video that allegedly shows the killing of two Scandinavian university students in a remote part of Morocco’s Atlas Mountains is likely authentic, Norwegian police said Friday. Norway’s National Criminal Investigation Service has been investigating the footage circulating on social media. “There is no concrete evidence indicating the video is not real,” it said.

Morocco’s general prosecutor also confirmed that a video in which the suspects swear allegiance to ISIS and threaten to carry out attacks is authentic, CBS News correspondent Holly Williams reports. Commenting on that video, the NCIS said that “neither Norway nor Denmark was mentioned in the video, nor was there anything specific about what action they should perform.”

Four men have been detained in Morocco, and authorities there consider the killings of two female students to be a terrorist act. The women from Norway and Denmark had been hiking, and two French hikers discovered their bodies discovered Monday with stab wounds in their necks, Williams reports.

It’s unusual to see a terror attack in Morocco, but not to find ISIS terrorists there. CBS’ Holly Williams notes that a number of ISIS fighters came from Morocco and have drifted back home after the collapse of their “caliphate” over the last two years.

Just how tied into ISIS these particular terrorist butchers might be is an open question. As of yesterday, ISIS had not taken credit for the murders, and the video had not appeared on their own social-media networks. However, New York Times reporter Rukmini Callimachi noted yesterday that the video makes their ISIS connections clear, as well as their familiarity with ISIS propaganda:

4. When I hear these terms, I know that the people involved have – at a minimum – spent time soaking in ISIS' propaganda, because that's how ISIS talks. More disturbing is a video showing a young woman being decapitated. Her face is pinned down under the foot of her attacker.

— Rukmini Callimachi (@rcallimachi) December 20, 2018

6. But here is a concerning development: A European official close to the investigation confirmed that the beheading video was sent by private messenger to friends of the killed Danish woman by unknown senders who appeared to have Moroccan profiles. Police is investigating.

— Rukmini Callimachi (@rcallimachi) December 20, 2018

Good Lord. The existence of the video is bad enough, but to send that barbarity to the friends of their victim is doubly horrific. It should double our resolve to stamp out the insane radical-Islamist ideology that drives ISIS, a poison it hopes to keep spreading around the world.

And that’s not all. They want their caliphate back too, as they proved yesterday. They launched an attack on Hajin, the same town mentioned in the video:

Islamic State used car bombs and dozens of militants in the attack near Abu Khaser village in the Hajin area of southeastern Syria, where the SDF and coalition are battling to wipe out the last Islamic State pocket east of the Euphrates River, the SDF official Mustafa Bali said.

That’s something to keep in mind as we strategize on national and global security. The more ISIS reconstitutes itself, the more of these videos we can expect to see.