I don't think it's Mihar or Harsh..how can Harsh give an interview stating he is the killer..he would violate his contract with Balaji...he has to have given the interview on Balaji's order, to add more conterversy.
Whoever the killer is both Karan and Mihar are protecting him/her or they are doing it under duress. I still think it is Abishek..but somehow Shoba is involved. She has not been seen and both Mihar and Karan would sacrfice their lives for her.