Tarit said the DSI would now seriously crack down on these offenders - who often changed the names of the shops and owners but rarely the location - and the tour guides and tuk-tuk drivers who act as their accomplices. The DSI already has a list of some 20 suspicious jewellery shops to check out. The agency would soon join with the Tourism Ministry to open an operations centre to stamp out the racketeers targeting tourists, he added.