why does poole believe that his master has been murdered?

Poole reveals that he has come to Utterson in desperation. He is severely concerned about Dr. Jekyll's well being, as the man has been locked in his cabinet for weeks and allows no one to see him. Poole admits that he believes there has been "foul play", but refuses to go into specifics. Utterson has long been suspicious of Jekyll's behavior and has worried for his friend. Thus, upon hearing of Poole's concerns, he quickly agrees to help. The two men leave Utterson's home and head over to Jekyll's.