The Mage Country's traitor was discovered three days after archmage Akama's assassination.
The traitor was Trant Sodar, an archmage of dark witchcraft. He excelled in death summoning and rune creation. He only lacked a convincing research result which was sufficient enough for him to join the Truth Symposium.
It was discovered that he was directly connected to the Chaos Abyss. He received orders from someone high up in the Chaos Abyss to murder his comrade, archmage Akama.
I wasn't curious at all how the traitor had been discovered. The Mage Country had so many random mages with different specialties. Plus, Bardi's specialists had also been investigating. The assassin had also acted right under the watchful eye of the dragons. It would be strange for the assassin to have managed to escape discovery.