XP given by defeated playable-class NPCs

Ey guys,

I have a question about something I have not found in the books:
How can I calculate the experience given by playable-class NPCs?

i.e. How much experience does my group gain if they defeat a lvl 3 Warlock?

I have tried to do a reverse engineering from the NPCs in "Sinister Stone of Sakkara", but my maths does not work.
i.e. The Lady Below has XP 660 and she is lvl 5. So, following the table "Monster Experience Points" in ACKS p. 114, she has a base of 200 and each special ability gives an extra amount of XP 150. I cannot reach the 660 amount. However if I consider her as HD 5+, her base is 260, and each special ability is an extra 200. Thus, she would be a 5+** monster (their special abilities would be those gained through leveling beyond lvl 1: 
lvl 2: arcane striking
lvl 4: death healing
But, if I follow this logic, then the lvl 1 prisioners (room 71) have no sense to me:
Fighter lvl 1 = 10 xp (1HD monster)
Mage and Elven Spellsword lvl 1 = 16 each (1HD** ? but, which are their special abilities if they are a lvl 1 npcs? )

What am I missing here?

i think that spellcasting counts as "**"


IIRC, Arcane spellcasting is **, divine spellcasting is * - otherwise, it's done by plain HD in the case of fighters or thieves. 

That sounds right. Thank you very much.