Which of these phrases are not a threat?

The phrases in question:

I may kill you

I may not kill you

Which of these phrases would you not get in trouble for saying to a police officer for example?

For example if I say "you may not pass this line" reads as a directive that says do not cross this line. Now when I use the same scheme and say "I may not kill you" sounds like I intend to kill you, but am reconsidering it.

I know people like to say things like "I'll kill you... In Minecraft" etc. This is kind of where this thought came from, surely one of these phrases must be acceptable language right?

Yeah I know you shouldn't say either one, but I just find it a curious thought. I appreciate you entertaining this question