Background
An egoistical wizard (Ego) in an arcane academy has invented a new spell. One of his colleagues, a curious wizard (Cur) found out about this new spell and stole a copy (on scroll). Cur decided to share his findings with another wizard but not until he had made a copy for himself. The wizard who got the scroll handed to him (Gnu) is of a political branch at the academy whom feels strongly that all findings should be shared in between the members. Gnu decides to confront Ego and ask why he tries to keep things secret and tells the Ego that he will take the case before the ruling circle of wizards.
The Crimes
Ego realizes that if Gnu takes his scroll before the ruling circle his spell will become available to all. The spell is not such a big deal apart from coming with the [evil]-descriptor, Ego's motive is protectionism. Ego decides to kill Gnu. He uses knock to enter Gnu's quarters and kills him in his sleep by the use of Gnu's own staff. (Coup de grace). He leaves under the protection of invisibility. Most wizards sleep at night, for eight hours no less.
In the morning Gnu is found dead. Since no magic was used to kill Gnu most wizards suspect the murderer being one of the servants. They use various magics to expose the murder. By the use of speak with dead the wizards learn nothing since the victim was not aware of the attack that killed him. The wizards don't use commune since that is a divine spell (and as such frowned upon by the wizards.)
Cur is scared stiff by the murder on Gnu. Not that he suspects Ego but because Cur and Gnu has been more than condecending towards the "magically challenged servants". Cur fear that he might be killed too. He reports his fears to the ruling circle.
Ego becomes aware that Cur is talking to the ruling circle and fears that he might mention Ego's new spell. After making sure that Cur didn't tell the circle something along those lines he decides to kill Cur anyway, just to be sure. Ego knows that his spell has [evil] as a descriptor and that the business with Gnu and the new spell might incriminate him. After all, the wizards aren't stupid.
The spooked Cur casts a ward on his door as he is afraid the servants might break in and kill him. Ego uses scrolls stolen from Gnu in order to by pass the ward, enter and leave. (Dispel magic, knock, invisibility). He enters Curs room and kills him with a heavy candle holder. Ego takes the candle holder with him and hides it.
Development
The next day the characters arrive and are being told that they can stay only if they don't interfere with the current investigations going on regarding the recent killings. The characters are assigned seperate rooms. Ego is content at this point as he has made sure no one will learn about his new spell.
The players can find the following evidence:
* Gnu's staff has blood on it.
* Several scrolls are missing from Gnu's bookshelf: one dispel magic, one knock, one invisiblity and the new secret spell. Gnu kept a ledger of all spells in his bookshelf. No one has heard of the new secret spell.
* A candle holder is missing from Cur's room.
* The doors of both victim's quarters are unlocked. (Most wizards lock their doors but arcane lock is rarely used since spell slots are better used elsewhere, and besides won't protect them against knock anyway.)
* The servants claim innocence.
If the characters investigate, Ego becomes nervous and first tries to scare them off (by the use of magic of some kind) and then he tries to kill one of the characters. If that doesn't work he is prepared to murder the lot of them. He won't use political means to have the characters removed since this might incriminate him. However, some other wizard is more than likely to do this anyway.
Divinations and other spells:
* The higher ranking wizards belonging to the academy are likely not at the academy. They are out adventuring since that is the best way of earning XP enough to research spells and crafting items.
* The deceased are not aware who killed them.
* There are no divine spellcasters in the academy. Character's with the ability to cast divine spells are not just discouraged from using them (they interfere with the purity of the weave, or whatever) but moreover the wizards will never accept divine spells as proof since they don't trust the gods and are somewhat jealous of divine power.
* All spells work as normal on the academy. Divination is likely to tell the players "the murderer is an arcane spellcaster protecting what is his".
* Ego is the only person in the entire academy (including servants) that registers as evil. Ego does not protect himself. However, several other wizards have cast nondetection (or even sequester or mind blank) to protect their integrity.
