India, Feb. 5 -- A handwritten diary recovered from the room of three minor sisters who died by suicide in Ghaziabad has emerged as a key piece of evidence in the police investigation, offering insight into the girls' emotional world marked by a deep fascination with Korean culture and turmoil at home.

Police is probing the triple suicide at Bharat City Society. The sisters -Nishika (16), Prachi (14) and Pakhi (12) - jumped to their deaths from the ninth floor of the residential complex early on Wednesday.

The girls were rushed to the hospital, but declared brought dead. Their father, Chetan Kumar, has claimed that the girls had been playing a Korean game for nearly three years and had stopped attending school during this period.

The d...