There's a bug in PH 1.9 that when you kill someone, they'll suicide instead of giving you the kill. It's pretty game breaking for many players, as killing is needed to replenish health when you're away from the control point. It happens randomly, but it's common.
This bug report makes no sense... Are they killing themselves, or is the game declaring that they've been killed by the world with no assisters?
It makes perfect sense. 1. It's a bug in PH 1.9 2. It happens by chance when you kill someone 3. It shows the player's death as suicide 4. I said they'll suicide INSTEAD of giving you the kill. It's pretty obvious, a world/engine death