The pool nobody saw

Nothing can be built in a protected area. Even so, a swimming pool appeared, with little steps, lights and an awning for when the inspectors come by. Some clues in this case come as riddles. If one stumps you, a hint will solve it. 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

• Ascensão, the council inspector: She went to see the pool three times. Each time it was covered with an awning and she believed it was a flowerbed.
• Bartolomeu, the neighbour: He lives next door and sees nothing. He has a pool too.
• Celeste, the landscape architect: She drew the plans. On the plans, the pool is called a 'decorative water feature'.
• Dionísio, the lifeguard: He was hired for a pool that officially doesn't exist. He's paid full time.