The evidence is just overwhelming. I will walk you through it and I am sure you will reach the same conclusion.
Abbas was an ex-political prisoner due to his participation in illegal protests organised by the unlicensed Haaq Movement. Abbas regarded himself as an active member of the opposition. Haaq is known for it's undeclared hate of the existence of the US Naval Base in Bahrain.
Abbas worked as a security guard for a Disco/Bar in a Hotel in Ghudiabiya. This particular bar is frequented by American navy men. He was religious. It is possible that he may have made offending remarks that pissed off one of the Bar goers. It is also possible that he may have been mistakenly considered a threat to the lives of US navy men and thus must be exterminated. Another assumption could be that an intoxicated and psychotic US marine killed him “just for the kicks”.
Let's consider the events of the shooting. It was past 2 AM, at this time most bar/club goers start returning home full of alcohol, thus, the third assumption is highly probable here.
When Abbas was shot, the guards standing next to him said that they did not hear the sound of a pistol/riffle firing the bullet. This means that the pistol/riffle used had what is called a sound suppressor of some sort.
The bullet did not come out of his scull. This proves two things, first that the bullet was fired from very long range; thus, it could only be a sniper riffle at this accuracy. Second, that the riffle did not have a large calibre ammunition otherwise a massive brain trauma would've occurred at the entry wound. The medical report concurs with my conclusions.
Based on this the only weapon that could've killed Abbas is this
The US Navy Mark 12 Mod 0/1 Special Purpose Rifle with medium calibre ammunition and a sound suppressor used during Operation Iraqi Freedom.
This weapon is available only to US Navy SEALs....