The USB stick that came back

One of the missing USB sticks turned up on a bookcase, between two copies of the rules of procedure. Nobody put it there, nobody saw it arrive and everybody recognised it. Some clues in this case come as riddles. Four people and one piece of evidence: 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

• Albino, the lost property clerk: He has received umbrellas, false teeth and a vote of confidence. He had never received a USB stick.
• Berta, the librarian: She demands silence in the library. Since the break-in, silence is all anyone hears.
• Cristóvão, the first-term MP: He still gets lost in the corridors. He says that's how he ended up in the leader's office.
• Dionilde, the trainee journalist: She wants a scoop. So far all she's got is a USB stick.