Complex sentence: He tells Sagara that one of his agents, one of the twins mentioned below, has killed Kaname, when in truth, Leonard Testarossa's Arm Slave bodyguards killed the agent.
Split into simpler sentences: He tells Sagara that one of his agents, one of the twins mentioned below, has killed Kaname. However, in truth, Leonard Testarossa's Arm Slave bodyguards killed the agent.