The two photographs that accompany the e-mail are unrelated. At this point, it appears a prankster put them together with a fabricated background story.
The soldier pictured in the top photo is a member of the 28th Infantry Division (Mechanized) of the Pennsylvania Army National Guard. The picture was snapped not in Iraq (where this serviceman has yet to serve) but Kosovo, specifically, just outside Camp Bondsteel. The young man is not a sniper but a Signal Systems Support Specialist.
He has housed a number of photographs of himself on the Web, many of him toting or firing rather impressive looking weapons. The snapshot in question is listed under "Weapons" as "Barrett .50 caliber sniper rifle - M82A1."
Those who are sharp of eye had already noted the KFOR (Kosovo Force) insignia that was clearly visible and that the serviceman pictured was wearing a uniform with a woodland camouflage pattern (rather than desert fatigues), which did prove all along that the top photo did not match the story being given about it.(The "Green Zone," more formally known as the International Zone, is the heavily-guarded area of closed-off streets in central Baghdad where U.S. occupation authorities live and work.)
We have an unconfirmed report that the second photo depicts an insurgent killed in Mosul by the Iraqi National Guard on 8 December 2004. The dead man, we're told, had been one of seven enemy combatants (not suicide bombers) ordered to emerge unarmed from a mosque in that city. They resisted, and all were killed.