When is a wordly consequence a karmic retribution? Let me illustrate this question with an example: Assume "A" killed someone intentionally, as a consequence the police took A and he is in jail. After all his/her time in jail, will A be free from his Kamma OR A will still need to experience being killed as a consequence of his/her actions?

So, when do worldly consequences "clean" Kamma and when don't they? 
Sorry for the example involving killing, it is just to illustrate.
Worldy consequences don't purify a persons kamma, unless the worldy consequences that happened were caused by that specific kamma.