Killer Replay is a feature introduced as part of the 2015 Winter Update.
Killer Replay gives you the ability to watch your death from the eyes of the enemy who in which killed you. Killer Replays can be skipped with the key bound to Jump (Default Key: Space) and watched once more with the reload key (Default Key: R).
The Killer Replay interface includes information like the name of the player who killed you, the weapons in their loadout, their health and armor status, and your character.
By default, Killer Replays automatically start upon death. However, players can change this at anytime from Game Options.