Hatab had been subjected to arbitrary beatings since he arrived in the camp, because the Marines believed he had been involved in the rape and torture of Jessica Lynch. Hatab was already in very bad shape when Hernandez was ordered to hose him off, burn his clothes, and tie him to a stake, so he wouldn't foul other prisoner's clothes. Hatab had been beaten so badly he had lost control of his bowels, and was covered in excrement.
Hernandez was ordered to haul Hatab by his neck, so he didn't foul his own uniform. A post-mortem concluded that someone had broken the hyoid bone in Hatab's neck, and that this had caused bleeding that caused him to suffocate.
Hernandez was not held responsible for Hatab's death.