New Delhi, Aug 3 (IANS) The Central Bureau of Investigation (CBI) Wednesday registered four cases for manipulating the entrance exam results of the All India Institute of Medical Sciences (AIIMS), said an officer.

The CBI registered four separate cases for rigging of the post-graduate and one graduate entrance results, he said.

The first case registered by CBI pertains to rigging of the results of All India P.G. entrance exam in January 2010. "In the exam, optical mark recognition (OMR) answer sheets of seven candidates were interpolated. These candidates succeeded in getting admissions in different Medical colleges of India," said official.

The second case registered was of rigging of results of MBBS entrance exam held on June 2010. In this exam, the answer sheets of six candidates were changed. In this one candidate succeeded in getting admission in AIIMS, said official.

The third case was of P.G. entrance exam held in November 2010. In this eight candidates got admitted.

The fourth was registered for rigging of AIl India P.G. entrance exam held in January 2011. In this exam, four candidates succeeded in getting admissions.

The cases have been registered against kingpin Mahipal Singh and his associates along with the candidates.