Complex sentence: Willoughby brings Mildred in for questioning after she injures her dentist in an altercation in his clinic, during which Willoughby begins coughing up blood, a sign that his illness is becoming severe.
Split into simpler sentences: Willoughby brings Mildred in for questioning after she injures her dentist in an altercation in his clinic. During the interview, Willoughby begins coughing up blood, a sign that his illness is becoming severe.