Complex sentence: The rumour states that a hired assassin stopped Trujillo's car with a rifle shot, allowing a gang of partisans to finish him off; furthermore, Thomas also learns that the assassin was an Englishman, whom he is able to identify as Charles Calthrop.
Split into simpler sentences: The rumour states that a hired assassin stopped Trujillo's car with a rifle shot, allowing a gang of partisans to finish him off. Additionally, Thomas also learns that the assassin was an Englishman, whom he is able to identify as Charles Calthrop.