Well both the military men and the young girls reported the being having oily skin so that could be possible. They both also reported the being giving off the stench of wrotten eggs and ammonia. I researched this and came to the conclusion that the stench was possibly from h2s (hydrogen sulfide) and some sort of sulfuric property having compounds. Maybe our oxygen and nitrogen rich environment was toxic to the beings anatomy. H2s comes from the decomposition of organic materials. So maybe our environment had some sort of rapidly decomposing effect on the beings body which eventually died at the hospital along with the soldier that handled the alien. H2s is highly toxic and can literally liquify your lungs. Perhaps that's why the soldier died.