Complex sentence: Captain Biggs and Sergeant Green, who were "investigating" Ludlow, arrive at the scene, and Biggs reveals that they used Ludlow to bring down Wander by opening Ludlow's eyes to the corruption going on within his unit.
Split into simpler sentences: Captain Biggs and Sergeant Green, who were "investigating Ludlow", arrive at the scene. Biggs then reveals that they used Ludlow to bring down Wander by opening Ludlow's eyes to the corruption going on within his unit.