If Talwars did not hear any scream of their daughter on that fateful night, It is only possible when, they were not at home. Because they used to go out in midnights leaving their only daughter alone at home. Krishna had knowledge of their movements, and he took the adavantage of that. When Talwars return home in the early morning they found their daughter murdered. To hide their fault that they left their teenage daughter alone at home in midnights, they started lying and misleading the police. So, if Talwars are not involved then they are also responsible for murder of Arushi.
