The gemara derives from pasuk that zomemim on galus get malkus and not galus.Logically speaking though how can we possibly give zomemim galus if theres no Goel hadam thats pressuring them to stay in Arei Miklat as opposed to the person who they testified about would be in a more pressuring situation being that the realatives of the dead person can kill him oustide galus.
aaron Massry, brooklyn Ny
The pressure of a Goel ha'Dam is only for a Rasha that is going against the Torah. In other words, the Torah mandates that a person who kills accidentally must stay in the Ir Miklat in order to achieve atonement. The Torah merely adds that if he does not listen to the Torah and leaves, he is liable to be killed by the Goel ha'Dam. However, the Torah's sentence of Galus is irrelevant to whether or not there is a Goel ha'Dam.
All the best,
Yaakov Montrose