Complex sentence: By then, the gunman is determined to somehow retrieve the incriminating bullet from the crime scene, and taking advantage of her experience with corpses, he forces Letitia to remove the head from the bartender's corpse.
Split into simpler sentences: By then, the gunman is determined to somehow retrieve the incriminating bullet from the crime scene. Taking advantage of Letitia's experience with corpses, he forces her to remove the head from the bartender's corpse.