The agency registered the first case in connection with the post graduate exam held in January 2010 where answersheets of seven students were allegedly interpolated.
All the students whose sheets were allegedly rigged got admissions in MD/MS courses in other medical colleges, CBI spokesperson Dharini Mishra said. The scores of the AIIMS post graduate entrance facilitates admission in other medical colleges too.
The agency has also registered another case at the undergraduate entrance examination level in AIIMS. The exam was held in June last year and six answersheets were allegedly interpolated of which one of the students managed to secure admission in the prestigious institute.
The two other cases pertain to AIIMS PG Examination in November 2010 and January 2011 in which answersheets were fudged to ensure admission in the scarce post graduate seats at the institute and other medical colleges.
In the November 2010 case, the answersheets of eight candidates were interpolated.
"As a result all the eight candidates were successful in getting ranks in the merit list and out of them three candidates also took admission in MD/MS course in different departments in AIIMS," Mishra said.
She said in January 2011 PG admission answersheets of four candidates were interpolated and as a result all the four candidates had succeeded in getting admissions in MD/MS courses in different medical colleges.
Earlier, on June 2, the CBI had registered a case pertaining to manipulation and rigging of AIIMS PG Entrance Exam 2011, held on May 8 in which six persons including kingpin of the racket was arrested.