Raids at a businessman's house in Assam revealed around Rs 1.55 crore in new currency notes.

Highlights Over 200 searches for black money have been conducted since the notes ban

Serial numbers on Rs. 2,000 notes helped investigators track launderers

CCTV footage from places where big notes are spent helped in the raids

There have been over 200 searches across the country for black money since the notes ban and crores have been found in new 2,000-rupee notes that are not so easily available at banks and ATMs yet.Behind the raids, say sources, is intel provided by government "informers" lurking at "strategic points" to track the movement of high currency notes. This may mean someone's watching you at a bank or a market, but sources in the Income Tax department have refused to reveal anything.The serial numbers of the Rs 2,000 notes has helped investigators in tracking down the bank from where the notes were issued and where officials may be involved in helping launder money.CCTV footage from places where bigger notes are likely to be spent - like jewellery shops - has also contributed to the raids. An RBI officer and a casino owner were among those arrested in Bengaluru today after raids over the past few days. K Micheal, a senior special assistant with the RBI, was arrested by the CBI after he was reportedly caught helping convert more than Rs 1.50 crore.In Assam, raids at a businessman's house in Guwahati revealed around Rs 1.55 crore in new Rs 2,000 and Rs. 500 currency notes. Lakhs were found during raids in Rajasthan, Madhya Pradesh and Gujarat.Tax officials say around 120 crores has been seized till now and 1,500 crores in unaccounted wealth have been traced.Officials have pieced together how bundles of new notes are being routed out of banks - a question raised by many since images of new notes stacked up after raids started emerging.Sources say those with black money have been known to take identity cards of labourers in bulk and hand them to bank officials, who obliged by exchanging the old notes with new ones.

New notes are being bought at a higher value by black money hoarders.Rajnish Kumar, the Managing Director of State Bank of India, told NDTV that there is fraud, but it is only a fraction of the transactions and can be easily detected.