Why didn't it count as self-defense?

"I cannot speak of the first murder, only of the second. From what I saw, Mr. Moon and Mr. Kim were in a verbal dispute, but never did Mr. Moon lift his hand. In fact, it was Mr. Kim who threw a punch his way, greatly escalating the use of force. In other words, Mr. Kim instigated the fight when no threat of harm was imminent."

- Witness