More than 58,000 citizens of the U.S. lost their lives in (or as a consequence of being in) Vietnam during the Vietnam War.  My uncle was one of them...
He was one of the many men and women who served their country honorably.... 
He was drafted into the U.S. Army and was sent to fight in Vietnam...
 
Now, my question to the vine is this, "Was my uncle murdered or was he killed?"
 
My opinion is this:  He was killed in the line of duty, serving his country...  I do not believe he was murdered... I do not believe a warrant should be sworn out for anyone's arrest for his murder....
 
So, how does this relate to comic books and AvX in particular?
 
Was Charles Xavier murdered or was he killed in battle?
1: Utopia was a sovereign nation.
2: Charles Xavier was not a soldier of the U.S.
3: Charles Xavier was not an agent of SHIELD.
4: Charles Xavier was not a member of the Avengers.
 
Now, I know he did not need to be a member of any organization to do what he thought was right, or to fight the good fight... But my question still stands...
- Charles Xavier went onto foreign soil, uninvited. 
- Charles Xavier engaged in a battle in which he KNEW he could die.
- Whether or not it was right or wrong to do so, Charles Xavier was fighting a war...
 
IF things had been different, for example:
1: IF Charles Xavier were an official agent of SHIELD or member of The Avengers.. AND
2: IF Charles Xavier had attempted to capture Scott Summers on AMERICAN SOIL (U.S. territory)
 
I could understand Cyclops killing of Xavier being viewed as a murder...  But what I saw in AvX was a war, fought on foreign soil....  In war, one does not MURDER the enemy, they KILL the enemy...  It's a sad reality...
 
One more question to ponder....
If you still believe Charles Xavier was murdered, exactly WHICH court should issue the warrant for his arrest?  He was murdered in a country OTHER than the U.S.  The U.S. has no authority to issue warrants for crimes committed in other countries.   You may not like that, but that is the way it is....
 
If King Namor were to kill Tony Stark within the borders of Atlantis - would the U.S. issue a warrant for his arrest?
If T'Challa or Queen Shuri killed Peter Parker withing the borders of Wakanda - would the U.S. issue a warrant for their arrest?
If Queen Elizabeth killed Wolverine (some of you are cheering this) within the walls of Buckingham palace - Would the U.S. issue a warrant for her arrest?
 
The answer to all three questions is "NO."   The U.S. has no authority to prosecute crimes committed in other countries...
So, tell me, exactly where did the warrant for Scott's arrest (on the charge of murder) come from?  What court issued it?