After your 12th you should go for either B.Sc (Forensic) OR B.Tech (Biotechnology).
The minimum Aggregate percentage in high school exam should be 60% to pursue either B.Sc Forensic OR B.Tech in Biotechnology.
You may choose either one, which can lead you to the forensic department. Although after B.tech in biotechnology you will have better opportunities as Finger Print Expert, DNA Fingerprint Expert, Lab Technician etc...
In B.Sc Forensic science you will get all the details how will be the interior environment of an forensic lab, technologies followed etc...
Its the detail on your options, its your decision to opt one among the two.
Best of luck!!!
If you have any further questions, please feel free to ask!