What does a detective do?

A detective is a police officer who gathers information on a crime that has already occurred or will occur and formulates a plan to solve the crime or to prevent it from happening.

For example if Moshe’s bike got stolen and so did Yoni and Eli’s a detective will interview all the parties (people involved like the boys) determine the type of bike stolen (by color make and model) and maybe do a sting operation (a secret plan to catch a criminal) by leaving those types of bikes out on the street to lure the thief there — and then the detective makes the arrest right on the spot.