BJP MP Subramanian Swamy on Thursday said Congress president Sonia Gandhi and former prime minister Manmohan Singh should be summoned by the CBI on the AgustaWestland helicopter case."(Going by) the Italian court judgment, Sonia Gandhi, Manmohan Singh, Ahmad Patel and Oscar Fernandes should be summoned to the CBI headquarters and asked what they know about this (AgustaWestland helicopter case)."If they speak the truth, they will have no problem. But if they tell lies, they will have to be prosecuted," Swamy said. Defence Minister Manohar Parrikar on Wednesday said the probe in the AgustaWestland helicopter case will focus on those named by the Italian court.