hi,

see there is various type of Investigation position available. general eligibility criteria is candidates must complete 12th or diploma course from a recognized education board. generally the recruitment for investigator seeks candidates who has law enforcement or military , or a degree in criminal justice or a related field of study. however I would suggest to go for forensic science or criminal law or criminology would be best. however In india there is less of diploma courses available for mentioned stream. so it would be best to pursue graduation and then apply for relevant job.