"Murió" versus "se murió", any difference?
No, they are the same. The se is sometimes used to emphasize something (comer algo vs comerse algo), but wrt death there really aren't many different levels of intensity.
Thanks. Another question, does "matarse" (as in él se mató) mean the same as morir(se), or is it synonymous with suicidarse?
"Él se mató" literally means "He killed himself", as opposed to "Él (se) murió" ("He died").