Last night someone broke into a top secret science laboratory and stole a new antibiotic class which is known to defeat all strains of bacteria. Unless this antibiotic is located, there is a possible risk that it will be distributed and sold on the black market. This will most likely result in the evolution of resistance strains of bacteria, so the criminals have to be caught. The robbery was carried out yesterday evening between 19 and 22, and the police have three suspects. They have an alibi and claim that :