A good detective always needs intel guys, who can be the eyes and the ears where the detective can't. You managed to make a deal with a fruit monger. Last week he sent you a text, he was on something big. However, he didn't appear at the meeting. Someone got to him before you. He's a smart guy, so he must have left some trace or clue in his house. You enter the key to his door and it unlocked instantly.
Surely enough, the place is a wreck! Because of this, your alarm bells went off. Your tipper indeed caught a huge fish and somneone else knows about it. You examine the place further and found an important clue. A metal lighter is lying underneath the table. It can't be the fruitmonger's because he doesn't smoke. You had a secret code, though. He carved symbols into fruits and vegetables. You better find them fast!