Is it first degree murder or manslaugter?
I would think either 1st or 2nd degree murder. Just because you didn’t intend to kill the person you did kill, you did plan on killing someone. Manslaughter is for cases where you do not intend to kill someone, but through neglect, you do (example; car accident that you are at fault for that kills someone), or if it is intentional under mitigating circumstances (example: heat of passion).