NEW DELHI: The CBI has issued a lookout notice against former Kolkata police commissioner Rajeev Kumar , whose custodial interrogation it has sought in connection with the Saradha scam , to prevent him from leaving the country, officials said Sunday.All airports and immigration authorities have been alerted by the CBI this week to prevent him from leaving the country and intimate the agency on any possible move, they said.The agency wants custodial interrogation of Kumar, a 1989-batch IPS officer, in connection with Rs 2,500 crore Saradha ponzi scam as he was heading the Special Investigation Team of West Bengal Police to probe the case before CBI took over, they said.The CBI had told the Supreme Court that custodial interrogation of Kumar was necessary as he was not cooperating with the probe and he was 'evasive' and 'arrogant' in answering queries put to him during his questioning by the agency.Solicitor General Tushar Mehta, who was appearing for the CBI had said Kumar was the in-charge of investigation by the SIT and had allowed the release of mobile phones and laptops, containing crucial records of alleged involvement of political functionaries in the scam, which were seized from the accused.Mehta had said the seized mobile phones and laptops were not even sent for forensic examination and material evidence was destroyed in the caseThe apex court had last month asked CBI to furnish evidence for seeking custodial interrogation of Kumar in the Saradha case, saying it has to be satisfied that the agency's request was 'bona fide and not for 'political purposes'.The apex court on May 17 had withdrawn protection given to Kumar from any arrest and had asked the CBI to proceed as per law."We have withdrawn the protection given to Rajeev Kumar vide order dated February 5," the bench headed by Chief Justice of India Ranjan Gogoi had said but gave a week's time to Kumar to approach competent court for anticipatory bail.Kumar had again approached the Supreme Court on May 20 seeking extension of protection claiming that the courts in West Bengal were not functioning due to lawyers' strike.This petition was rejected following which Kumar had approached a Kolkata court with an anticipatory bail.In the last week of January, the Centre and West Bengal government faced an unprecedented stand off after a CBI team which reached the residence of Kumar, then Kolkata police commissioner, for questioning him had to retreat after local police refused to let it enter and detained its officers.West Bengal chief minister Mamata Banerjee came in the defence of Kumar and started a sit-in to protest against the Centre's move.The Supreme Court on February 5 had prevented the agency from any coercive action against Kumar and directed him to appear and co-operate in CBI questioning at a "neutral place".He was questioned by the CBI for nearly five days at its office in Shillong from February 9 onwards.The Saradha group of companies duped lakhs of customers promising higher rates of returns on their investment, the CBI has alleged.Similar modus operandi was adopted by other ponzi companies like Rose Valley operating in West Bengal, Odisha and North Eastern states where gullible investors were duped, it said.The Supreme Court had ordered a CBI probe in which the agency has allegedly detected collusion of scheme operators, police personnel, politicians among others, the officials had said.