Obanikoro who was a senator during the administration of Goodluck Jonathan was accused of being involved in the infamous arms scam as N4.75bn arms funds was reportedly traced to his account.
Obanikoro arrived in Lagos from the United States on Monday, October 17 and went to Abuja some hours later.
There was concern that the senator would not report to the EFCC in Abuja but he later did and submitted himself for interrogation.
It reports that the EFCC is investigating a firm, belonging to two sons of Obanikoro, Sylvan McNamara for receiving N4.75bn arms funds from the office of the former National Security Adviser between April 4, 2014, and December 15, 2014.
Obanikoro had asked all Nigerians to help him beg President Muhammadu Buhari to try to extradite him from the United States and see how terrible the mission would fail.
He claimed that the charges against him by the EFCC were false and vowed not to honour the invitation by the anti-graft agency.
While his reason for his return is not clear yet, there is speculation that he may reach a plea bargain with the anti-graft agency.