The chorus on the bus

A week after the concert, the chorus was still playing everywhere, even on the local bus. And it was on the bus that someone found a forgotten microphone. Four people and one microphone: one person per row, one per column. Whoever is left alone with it in the same room is the one you're looking for.

Suspects

• Antónia, the bus driver: She plays the radio on the bus every morning. Since the concert, the chorus comes on every hour.
• Bernardim, the ticket inspector: He punches tickets and sings under his breath. He says he doesn't know the words, but he does.
• Celestina, the lady with the shopping: She takes her shopping trolley everywhere. Now everyone asks her what's inside.
• Duílio, the newspaper seller: He sells papers at the bus stop. Every front page that week had the same chorus.