West Bengal police has arrested Amiya Mahato, a close associate of the key accused in the Gyaneshwari Express derailment case, Bapi Mehto from Komasoli village of West Midnapore district. Jhargram Superintendent of Police Praveen Tripathi said Amiya is the seventh person to be arrested in the case, which is being investigated by the CBI. Mr Tripathi said said, Amiya's role in the incident is yet to be ascertained.<br/>