You still don't get it, what if you caught WRONG person, how is it going to give you justice?
If you had right person at the damn moment of crime, sure that is to defend yourself and loved one. That is the only time that is justified... as opposite as going to court with trial... ANYTHING is possible, bam could have killed innocent ones.
Kill is allowed ONLY in the event when a person or more is in present and clear danger... Dad killed pedophile WHILE Pedophile raped dad's daughter, that is in effect meaning protect Dad's loved one. That is when killing is allowed, not hour later, not tomorrow, not next year, not 10 years later, That moment of crime or NEVER.