“Unfortunately I just heard that he was arrested for only third degree murder and manslaughter.”
Do you have private information that suggests it should be a higher charge. If so, please share.
I heard a lawyer say that premeditation doesn't take a certain amount of time. You can decide to kill and do it in the same minute and that's enough for first degree murder. It's harder to prove without other actions to prove premeditation like buying a gun, but it still can be first degree. Eight minutes of kneeling is more than enough to show a planned intention to kill.