Passage: Callahan learns of Scorpio's hospital visit and a doctor reveals to him that Scorpio lives in a room at Kezar Stadium. Callahan finds him there and chases Scorpio, shooting him in the leg. Callahan tortures Scorpio into confessing where Mary is being held. She is found already dead. The district attorney scolds Callahan for his conduct. The police are forced to release Scorpio because they realise the evidence they collected will be inadmissible in court. Callahan is outraged. He continues to shadow Scorpio on his own time. The killer pays a man $200 to beat him severely and then says he is a victim of police brutality.

Question: How does Callahan find Scorpios location?
doctor