Hey Jithin,
You should have pursued 10+2 With PCB as your main subject. No problem with PCMB. Then after 12th there are many government and private universities in India which provides you BSc Forensic Science. Applying for each of them appear in the exam. And then obviously you have to crack that exam. Only then you can get into BSc Forensic Science.
Best of Luck
Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile