Kutty Kadai was seething with rage. The metal cash box that she kept in her shop had been stolen.
“Dada Dukaan is behind it, Officer!” she told Kamlesh Kaaval, the police officer who had arrived to
investigate. “I am certain of it!”
“How so?” asked Inspector Anjum Adhikaari, the other police officer on the scene.
“He owns and runs the shop across the road,” said Kutty. “It’s bigger than mine, so he tried to bully me and steal my customers. When that didn’t work, he stole the cash box that contained my daily earnings!”
“What a horrible accusation!” cried Dada. “I am an honest businessperson, not a thief!”
“Please cooperate, Mr. Dukaan,” said Inspector Adhikaari. “Ms. Kadai has registered a complaint against you, so we must search your shop for her missing box.”
Within minutes, Officer Kaaval found a blue cash box tucked away under a pile of Dada’s accounts books.
“Aha! I was right! He is the thief!” said Kutty triumphantly.
“Rubbish!” retorted Dada. “That’s mine! Two people can have the same colour cash box, you know!”
“Officer Kaaval, please dust the box for fingerprints,” said Inspector Adhikaari.

“Mr. Dukaan, please surrender your box’s key to us. We need it for further investigation,” said Inspector Adhikaari.
Dada gleefully gave her the key. The following day, the police were back at his shop, but this time, they arrested him for the theft.
“I knew it! I knew it!” Kutty rejoiced. “Not only is Dada a liar but also a thief!”

How did the police officers figure out that Dada Dukaan had indeed stolen Kutty Kadai’s cash box?