How can I get the player that killed the other player?

Hello there any way to get the player has killed other, ie to make a minigame two players and that when I ended can get the player that killed the other and place it in a variable.

 

PHP:

public function onDeath(PlayerDeathEvent $event)
{
    $player = $event->getPlayer();
    $lastDamageCause = $player->getLastDamageCause();
    if ($lastDamageCause instanceof EntityDamageByEntityEvent) {
        $killer = $lastDamageCause->getDamager();
        if ($killer instanceof Player) {
            //Killer is a player, set wherever you need it!
        }
    }
}

 

Thank you.