- all have hair-follicles
- from which have developed mammary glands
- all maintain a set core body temperature
- have a high metabolic rate to service the energy to do so
- have lost the nucleus of their red blood cells to carry more oxygen
- all have seven cervical vertebrae
- many of them have limbs with five digits; at least as embryos
- all have three teeny bones in the ear to transmit sound
- all have a clear common pattern of embryological development
post some pictures of hotel rooms on Twitter to see if anyone recognised the place. Clearly you don't want to focus on the colour of the carpet or the wall-pictures because these get changed and upgraded in hotels that aren't total flea-pits. But the over all structure of the room, the position of the bed w.r.t the window and the en-suite and the light-fittings, are much more likely to be diagnostic because they embody more structural inertia. Twitter is huge and the number of people who holiday in Mauritius AND use Twitter is considerable and soon enough a match [R: scene-of-crime above (with person blanked out) / promotional material below] popped up in the Marlin Creek Hotel on the island.
Europol didn't appear to know that there was a parallel investigation going on in North America at TrafficCam. If you are nerdy about such things and can blow up the details in the pictures, then you can check out the electrical sockets which are madly and maddening diverse across the world. You couldn't do this location matching with Irish Pubs, they all have the same clutter.