Considering my target has a dwelling, and I have no previous records of aggression towards him, I would...
Watch him/her for many days, even months. learning their friends, their routine, and the circles they run in... Being inconspicuous.
I would obtain a small dosage of Iocane, A tasteless, scentless powder, that dissolves instantly in water, and can kill a man of 230 pounds(104.55 Kilogram) with 10 miligrams, wether inhaled, injested, or taken into the bloodstream.
On the date of my careful choosing, I would possition myself within their vicinity, while they are excluded, alone. Be it in the morning as they leave their house. At night when they return (preferably).
Armed with a small, silenced air powered bebee rifle, (easily obtained at a sporting or hobby store, Silencer homemade from carbide tubing, or obtained if you have a connection. I would have one of my pellets laced with the Iocane, previously mentioned.
Struck with this pellet, Making no noise, in the upper leg, or back if they hadn\'t thick clothing. they would feel naught more than a pin prick,
Within 10 minutes they would be lifeless, inside of their home. and i would be safely back from whence I came.
I know where you live
*wandering eyes*