There are assassins in .53 although they are hard to get. I dont know what requirements there are but there is the option to build a faceless man or sorrowful man guild that will give you the option to hire, for a lot of gold, a highly skilled assassin (faceless men>sorrowful) to kill one person. It is a great idea that I hope will be perfected, because it is currently flawed, in the 1.0 version