Reasons why indrani mukherjea killed her daughter:
1. Indrani was afraid that her daughter would reveal her secret because for years Sheena was told by her mother to tell everyone she wasn't her daughter but was her sister.
2.sheena was in a relationship with her step brother Rahul mukherjea. Cops believe it was an act of honor killing.
3.vikas , indrani's ex husband cooperated her in this act as sheena's property would be his daughter's vidhies property
4. Michael bora also claimed that indrani also tried to kill him by spiking drugs in his drink but he somehow managed to run away