The basic eligibility for BSc Forensic Science course is 10+2 with minimum aggregate of 70% in science stream.

So, you need to have science stream in your 12th, and qualify your boards with a minimum of 70%, then you can get admission into your choice of course.

Hii!
See, the Eligibility criteria for pursuing forensic science ourse after class 12th states that the candidate must have passed class 12th with minimum 50% marks in physics , chemistry, biology and / or maths. So, biology is compulsory for the course.
You can do forensic science without biology too, but, you will have to make extra efforts and learn the basics beforehand.
Hope this helps.
Good luck!