Bhagavad Gita, Chapter 2, Verse 19

He who takes the Self to be the slayer, and he who takes it to be the slain, neither of these knows. It does not slay, nor is it slain.

The soul can't be killed, and it doesn't kill. Whoever thinks otherwise doesn't understand it.

"I killed him" and "I was killed" both come from the same mistake: thinking the body is the whole story. It never was, so neither claim actually lands.