Constant "blackmailing" of former media executive Indrani Mukerjea by her daughter Sheena Bora and relationship with Rahul Mukerjea were among the reasons for her murder in April 2012, according to a CBI official.

The official, requesting anonymity, today said former media baron Peter Mukerjea, arrested yesterday by CBI, had played "a major role" in the murder of Sheena, his step- daughter.