The SRD describes Death Attacks as follows:
In most cases, a death attack allows the victim a Fortitude save to avoid the affect, but if the save fails, the character dies instantly.
- Raise dead doesn’t work on someone killed by a death attack.
- Death attacks slay instantly. A victim cannot be made stable and thereby kept alive.
- In case it matters, a dead character, no matter how she died, has -10 hit points.
- The spell death ward protects a character against these attacks.
The assassin's death attack is an instant kill, is even called "death attack", but is not protected by death ward as it's (Ex), not (Su). Is it a "death attack", and does raise dead fail to work on someone killed by an assassin's death attack?