New Delhi, March 9: The CBI has decided to call diamond jeweller Nirav Modi and his uncle Mehul Choksi to join an ongoing probe into the Rs 12,600 crore Punjab National Bank fraud after the absconding businessmen failed to appear before the agency on Wednesday. A Central Bureau of Investigation (CBI) official on Thursday said the agency received separate emails from Nirav Modi and Choksi on Wednesday expressing their inability to return to India. "We shall be writing to them again to join the investigation," the official said. He said the CBI had written to Nirav Modi and Choksi first on February 19 for an appearance on February 20. The second summon to Choksi was issued on February 23 asking him to appear on February 26. The agency then summoned both on February 28 to appear on March 7. Nirav Modi and Choksi have both responded to the CBI, saying they won't be able to join the investigation because their passports have been suspended. The CBI official said in their email replies the accused have not shared the "details of the countries where they are currently based" and also not "contacted the nearest Indian embassy". On February 24, the government revoked their passports. Meanwhile, the CBI on Thursday carried out searches at over eight locations of the officials of Choksi's Gitanjali Group in Mumbai and Chennai. "The searches in Chennai and Mumbai were carried on the leads that we gathered during ther questioning of the arrested" bank officials and others allegedly involved in the fraud. The agency has arrested over 19 persons so far. The Enforcement Directorate, separately probing the case, has attached properties of both the businessmen worth Rs 6,000 crore across the country.