Can diablerie be performed on a vampire who has just met their Final Death?

Question

I'm currently playing a Sabbat vampire following the Path of Blood in a VtM game. In our most recent session, I encountered and fought two Camarilla alastors who were hunting me for committing diablerie.

Before entering combat, I used the Burning Blade Thaumaturgy ritual to allow my sword to cause aggravated fire damage. By rolling well I was able to cripple one with my first attack, and then I used Celerity to perform another attack against the other. This time I rolled even better and dealt many more boxes of damage than his health chart could handle, and since it was all aggravated he instantly met his Final Death.

My group (myself included) couldn't decide whether the rules allowed me to commit diablerie on him since he was presumably decaying rapidly. They seem to imply the vampire needs to still be alive (as it talks about a struggle between the attacker and the victim), but fails to come right out and say it.

Can diablerie be performed on a vampire who has just met their Final Death? If so, how long after striking the deathblow does a diablerist have to drain the victim before his essence is lost?

Answer 1

Vampire the Masquerade rulebook on Committing Diablerie (p. 225) states the following:

A vampire seeking to commit diablerie must drain all the blood from his Kindred victim. Following this act, the vampire must continue to suck, for (according to Kindred legend) the very soul is withdrawn from the victim's body and taken into the diablerist's. The effort involved in diablerie is monumental for the vampiric soul is a greedy thing and clings tenaciously to unlife, hoping to regenerate its body and rise once again.

I've emphasized the parts that in my opinion rule against performing diablerie on dead vampire no matter how fresh. Since the vampire has already met it's Final Death, there is no soul to draw from the deceased vampire.

Answer 2

No, once Final Death occurs the soul or heart's blood you are trying to steal has been lost permanently.

From V20, p294:

The diablerist’s player makes an extended Strength roll... Each success inflicts one automatic health level on the victim... When all the victim’s health levels have been drained, the victim’s essence is taken into the attacker and the emptied body begins decaying immediately.

This is the basic (abridged here, refer to the full rules if you're running a scene) system for diablerie. It's very explicit that a vampire must literally drink away the victim's health levels in order to commit the act. Drinking their blood first is done mainly so that you can get to their inner core.

There needs to be at least one health level remaining with non-Aggravated damage in order for this to be possible. Therefore, you can't diablerize someone who has just met Final Death, because all of their health levels are lost. There is nothing left to drink.