In a major breakthrough in the Rs 2-crore fake cop robbery case in Girgaon, the Mumbai Crime Branch, which was conducting a parallel investigation, has detained the key accused in the case, even as a search for his associate is underway, police said.

The incident occurred on Friday around 6.10 pm near Laheri Building at the Fourth Khetwadi corner on SVP Road, when two men posing as crime branch officers allegedly robbed Rs 2 crore in cash from a 65-year-old construction firm manager.