Calcutta, Aug. 3 :    Calcutta, Aug. 3:  Khadim's owner Parthapratim Roy Burman may have returned home alone, unaided by police, but facts that have surfaced in the past 24 hours indicate that the multi-agency investigation into the eight-day kidnap-saga was on the right track from the beginning. 'One must realise that we are up against a formidable team high on resources, skills and resolution,' head of the special investigation team and inspector-general of police (South Bengal) Prasun Mukherjee said today. 'It wasn't a neighbourhood operation carried out by a cheap gang.' The CID has collected sizeable evidence, which points to the role of some inter-state gangs. A CID officer said the American Federal Bureau of Investigation (FBI) was called in to assist in tracking the phone calls routed through that country. The FBI traced two calls the Roy Burmans received three days after the abduction to the Amsterdam-New York-London-Chennai-Calcutta route. Officially, the administration still refused to shed light on the kidnapping. Chief minister Buddhadeb Bhattacharjee, like CID inspector-general Partha Bhattacharyya, was mum today as well. 'I shall make a statement on the issue when I am in a position to do so. You need not ask, I shall myself call you and explain everything. Wait till then,'' the chief minister told reporters. The police carried out over-night raids after Roy Burman returned home yesterday and detained several people for interrogation. Some key arrests are likely to follow shortly. 'We have enough evidence that proves that local contacts actually collaborated with the abductors and helped them get a safe passage from the scene of the crime,' an official said, adding that the CID was now trying to trace a police informer who was tipping off Tiljala businessman Chunnu about the raids. Officials are also combing areas in North 24-Parganas, where, they believe, Roy Burman was taken and given crude medical treatment for eight days. A West Bengal Armed Police official has been sent to Hyderabad where, the police believe, payment of the ransom was arranged. CID officials also visited Woodlands Hospital where Roy Burman was operated on today. The wounded shoe magnate asked for time to reconstruct the entire incident, officials said. The police have sought the help of their Mumbai and Uttar Pradesh counterparts to trace Hafiz Alam and Saudagar Singh, henchmen of Chhota Rajan's rival Fazl-ur-Rahman. Investigators feel they are among the main suspects in the case. They were told by their sources that the duo came to the city a week before the abduction. But Mumbai police do not seem to have much idea about the activities of Alam and Singh. According to the information they have provided, both come from Uttar Pradesh and initially worked for Chhota Rajan before switching loyalties to Rahman. However, investigators have learnt that both probably masterminded the abduction of a Bihar-based industrialist and a Gujarat businessman. Roy Burman's abduction is a signal to the city's businessmen that they are no longer immune from being the target of inter-state gangs. One theory doing the rounds is that the shoe baron was one of six city-based industrialists that the gangs may have targeted.