NEW DELHI: Businessman Karti Chidambaram, son of former finance minister P Chidambaram, failed to turn up on Wednesday, after he was summoned, at the ED headquarters here for questioning in connection with certain transactions in Aircel’s acquisition of Maxis.The ED is investigating the Aircel-Maxis deal under the Prevention of Money Laundering Act as part of the larger probe into the 2G scam.This was the third summons the ED had served on Karti , and in the last one the agency was specific in demanding his personal appearance, something the former has ignored so far posing questions to the agency instead. In response to one of the summons, Karti is believed to have asked what has been his offence? When contacted, Karti told TOI that the ED would be in a better position to answer on issues related to the summons issued to him.The ED is now contemplating taking Karti in custody for his refusal to submit to the investigation, sources said.P Chidambaram’s wife, Nalini , is also facing ED questioning this week in another unrelated case. She has been summoned by the ED’s Kolkata office in connection with the Saradha chit-fund scam.