In the unbearable midday heat, a Libyan patrol near the border with Tunisia comes across a black African man collapsed on the reddish-brown desert sand.
He is barely breathing, and officers try to revive him, gently, with a few drops of water on his lips.
The man is just one among hundreds of migrants arriving daily in Libya after being abandoned in the desert borderland by Tunisian security forces, according to Libyan border guards and the migrants themselves.
By the time they reach Libya, the migrants from sub-Saharan Africa are ready to drop from exhaustion, in temperatures that have exceeded 40 degrees Celsius (104 degrees Fahrenheit).