Since a murder seems to be constituted by the sum-total of events that transpire from the time the act-of-crime is committed to the time of actual death, "I'm standing at the scene of his murder" in such a circumstance would seem to me to be more precise and appropriate. Actually, this phrase does seem to be used in such a circumstance more often than not. Perhaps the reporter in question was being a bit overzealous for the melodramatic?