Important questions number one:
 

Why do they sterilize the needle before lethal injections?

prolly so they dont catch a dizease and die... prolly. werd

So the body doesn't get infected?

A dead body with an infection can't fight bacteria for shit, and damn that gets smelly. Until they bury it they'd have to deal with that.

to show that you're not barberic.

even though you're merking someone.

Come to think of it, needles come sterilized... I don't think you can get needles that haven't been sterilized. So why would they go to the trouble of making a needle dirty just so they didn't have to sterilize it for a lethal injection?