Kafeel just played into the hands of some sick minded peoples, but what made him to turn towards them, and who could have stopped him in doing this, is the main answer.
I feel that fault lies on 1. Parents, who have knowingly or unknowingly supported him for all his actions, they should have taken proper care and pulled out this brillient student from this hazardous activity.
2. The teachers of engineering college, when they found changes in him, they failed to inform the necessary authorities and parents, and do correcting measures. More fault lies in Dr. siddeshwara, when he noticed that he became reserved, he could have counseled him as a principle, but he failed, along with his other collegues, infact entire college is to be blamed, I feel that in that college there may also been some more kafeel in making, unless that college dont take strict measures, the pointer of fault crime is more on the college, than any other thing