What is the ranking criteria for 8 player FFA?

Obviously the first sorting key in the free-for-all Deathmatch is number of kills, but how are the players ranked in a game if multiple players have the same number of kills? In the latest game I played, I finished fifth having the same number of kills as the player in fourth. However, I had fewer deaths and more assists then them, so those stats probably aren't the secondary sorting keys. Is there a set secondary sorting method or is it just random?

Here are some examples from other games, one by me, one by my brother.

The game only counts kills when ranking players. Assists and deaths are not used, except implicitly in the kill score in the case of suicides.

When two or more players are tied, they are sorted by the time of their final kill: an earlier final kill is ranked above a later one. This is also true in Team Deathmatch if the two teams are tied when the time runs out: the team who scored their final kill the earliest wins the match.