The Torah puts a very high value on life in this world. Even when a life is shortened by accident, if that accident would have been prevented by taking normal precautions, the perpetrator is deemed a murderer and is confined to a city of refuge for an indeterminate period. The time of confinement (you could call it "incarceration", I suppose, but it is an entire city) is not indeterminate because the Torah doesn't specify length of sentence, but because the Torah specifies a sentence of indeterminate length: until the death of the Kohein Gadol/High Priest.
You could ask at least three good questions at this point:
- Why should the murderer's sentence depends specifically on the life of Kohein Gadol? What kind of behavior are we trying to deter?
- Why is the good name of the Kohein Gadol being besmirched in the press by being linked with murders (albeit, accidental ones)?
- Why should some murderers get a long sentence and others a short one? "Luck of the draw" doesn't seem like a very fair penal system.
I know they are good questions, because the rishonim ask them; Rashi addresses the first two, S'porno the third. All of them "on the spot"; Bamidbar 35:25
Rashi (in his first explanation) says that the Kohein Gadol causes the sh'china/divine presence to be infused into our lives; thus extending our lives. This murderer causes the sh'china to be removed from Klal Yisrael, thus shortening our lives. Note the murderer is not being punished (directly) for killing another Jew. Rather, he is being punished for his cavalier attitude toward life, which led to the death of a Jew.
Rashi addresses the second question in his alternative answer: the Kohein Gadal is mandated with praying for the welfare of his generation. The fact that this accidental death occurred on his watch shows that he was deficient in his duties. His name is being linked to the murderer because his actions (or lack thereof) are an accessory to the crime.
Hey... this isn't sounding so darn accidental any more!
Right; as the S'porno notes in his explanation.Not all accidental murderers are equally culpable. More than that, their environment also needs to be taken into consideration. When all the minutiae of details from the myriad of influencing factors are taken into account, the sentence is passed. HaShem causes the accidental death to occur at the precise moment that will leave the murdered in exile for precisely the amount of time that is required to exact punishment for his crime.
HaShem runs a tight ship and you are both passenger and crew member; enjoy the ride.