Following the First Battle of Geonosis, Quinlan Vos had gone undercover to learn more about the plans of the Confederacy of Independent Systems. He was not responding to Jedi Master Tholme's messages, causing concern among the Jedi High Council. Aayla Secura was sent to investigate.
Aayla Secura killing Zenex.
She met up with Quinlan, who was operating under the alias "Korto Vos," and rendezvoused with Khaleen Hentz, who had pick-pocketed a Separatist message from Zenex, a Falleen. The message was from Nute Gunray, who revealed that the Separatists were intending to strike the cloning facilities on Kamino.
After killing Zenex, and convincing the Neimoidian meant to intercept the message that his objective had been carried out, they relayed the message to the Republic.
Back on Coruscant, Count Dooku received a message from Tookarti, who told Dooku all that had happened. In truth, Dooku and Darth Sidious wanted the Republic to know about the attack, so they could repel the Separatists more easily.
Dissention was occurring amongst certain Separatist leaders, and those intending to replace Dooku were behind the attack on Kamino. The Sith Lords wanted the Separatist leaders to be humiliated by their defeat, and at the same time have Jedi killed in battle.