The radio van

The radio van was parked next to the venue, going live every half hour. During one of those broadcasts, the wireless microphone stopped responding. 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

• Adília, the presenter: She does the live broadcasts from the van. She said on air that the microphone was 'around somewhere'.
• Boaventura, the van driver: He always parks the van in the same spot. That day he parked somewhere else.
• Cíntia, the radio intern: She holds the cables and the coffees. That day she held something else.
• Dorivaldo, the doughnut seller: He sells doughnuts next to the van. He hears every broadcast without meaning to.