Abdulrasheed Bawa, Chairman of the Economic and Financial Crimes Commission (EFCC), appeared before Justice Sedoton Ogunsanya of the Ikeja High Court in Lagos on Tuesday.
He appeared to testify as a key prosecution witness in an alleged N1.4 billion oil subsidy fraud case.
The EFCC is prosecuting the case against Nadabo Energy and its chairman, Abubakar Peters, for allegedly obtaining N1.4billion from the Federal Government as oil subsidy, using forged documents.
Mr Bawa investigated the case when he was an operative of the EFCC.
The defendants are also being accused of inflating the quantity of petrol purportedly supplied to the Federal Government to 14,000 metric tonnes.