Kochi:A Tamil Nadu Crime Branch team is in Kerala for the last four days investigating the Rs 5.75 crore parcel van heist on the Salem-Chennai Express that is yet to be cracked even after a week. The Crime-Branch Crime Investigation Department (CB-CID) team from Chennai had arrived at the Ernakulam South station yard to check the bogies that had undergone an annual maintenance review two days before the heist. The bogies were at the yard for a week now and the probe team has verified the CCTV visuals besides cross checking telephone call records of officials and others . Since the episode, on August 9, when robbers decamped with Rs 5.75 crore, belonging to the Reserve Bank of India (RBI), from a train in Tamil Nadu not much head way has been made by the investigators. The thieves had gained entry into the coach of Salem-Chennai Egmore Express by cutting an opening on the roof of one of the coaches where boxes containing the currency were kept. It was after the train arrived in Chennai Egmore station and the bogie was opened did the crime come to light. By now numerous people from the railways and other establishments have been questioned. The RBI was transporting Rs 342 crore worth used currency notes from Salem to Chennai on three special coaches of Salem-Chennai Egmore Express train when the heist was carried out.