Q. When we express, either through writing or speaking, the Tefillah “Hashem Yinkom Damo”, what are we asking for? That the murderers be punished? What if the murderers are already dead or have been killed? What additional vengeance are we praying for?

A. Zohar (Vayero p. 107) and Rambam (Teshuvo 3:6) rule that the chastisement for the total and ultimate reshaim and evildoers is eternal.
Therefore, Horav Shlomo Miller Shlit”a pointed out that the punishment for the wicked who tortured or murdered innocent kedoshim, truly only begins after their demise.
Additionally it can affect subsequent generations of their descendants.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a