Maybe I’m wrong but I still believe when the cop kept his knee on an unresponsive man’s neck until he died, he is guilty of 2st degree murder which is not planned but when a situation arises and you use force to intentionally kill someone.
Yes, you are wrong.
If the cop merely held the man’s hand and sang a lullaby, the man still would have died.
The cop having his knee on the man’s neck did not cause his death. He did not die of asphyxiation. He died of ExDS.