Bug/Hack Question (recent ARAM game)

This is mostly a question of possibility...I'm not familiar with how easy/difficult it is to hack this game.

I was playing in an ARAM with a friend recently, and we noticed something strange. When my friend used a certain ability and killed an enemy champion, the kill went to another summoner on our team, even though they were nowhere near the kill, didn't throw any damaging abilities (that we saw), and didn't have a DOT ticks on them.

I give room for our missing something...it was all happening really quickly. But is it within the realm of possibility that there was a bug with an ability being invisible (or something like that) or a hack by that player? It would make sense with the quests going on right now for the Bilgewater event, but I don't have any evidence about this one incident.

Not calling for anything to be done; just want to document this in case it's helpful in any way. (I'm refraining from giving champion names at the moment to avoid giving the summoner's name in recent history. I can if that will help sort things out.)