Fruit out of season

In the middle of December, a box of cherries arrived at the club. Nobody ordered it, nobody signed for it and the golden whistle vanished the same day. Some clues in this case come as riddles. If one stumps you, a hint will solve it. Four people and one whistle: 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

• Adérito, the club receptionist: He took in the box of cherries and signed with a scribble. He says the scribble isn't his.
• Belarmina, the club cook: She made jam with the cherries. She says there's nothing in the jam but cherries.
• Cristiano, the team captain: He ate half the cherries before training. He says he was testing whether they were real.
• Débora, the club nutritionist: She banned out-of-season fruit. Nobody knows why, but she has her reasons.