Hey !
To get into CBI or CID basically you have to satisfy all the below conditions :
1) Must complete Graduation in any stream from a recognized University.
2)Criteria:-To join CBI you need to appear for CGPE exam i.e. Combined Graduate preliminary Exam which is conducted by SSC board every year.
3)Age must be between 21 to 25 years(For general category) (As  you stated your age as 35 you aren't eligible).
4)Must be a citizen of India
Hope this helps
All the best !

I AM EAGLY TO JOIN CBI, I HAVE KEEN INTEREST TO WORK WITH ORGANISATION LIKE INVESTIGATION, PLEASE TELL ME ONCE, COULD IT POSSIBLE TO WORK WITH , 

WAITING YOUR REPLY..........

THNX & REGRDS,

RAVI-RAJ