Mayor: Hello, guys and gals! Oh, boy. I wish I had a picture of your stupid faces.
Captain Harris: Mr. Mayor.
Mayor: Hello, Harris, you stupid twit.
Mayor: Oh, crapola.
Captain Harris: Proctor! You have been singing Christmas songs for the entire five hours of this stakeout. And Christmas is a good four months away. If you sing so much as one more note... I will shoot you.
Answer: Because they found jewelry from the last crime in his office. That's why he was shocked. They may be friends, but he knows he can't ignore evidence even for a friend.
lartaker1975