India, Feb. 6 -- As investigators piece together the family's life, they say it was marked by a series of complex and layered dynamics - from financial stress that began during the pandemic and intricate marital relationships, to years of school dropout and a growing sense of isolation the girls experienced within their home.

Investigators said the sisters, aged 16, 14, and 11, lived with their father - a 42-year-old stock trader - his two wives (who are sisters), a 13-year-old deaf and specially-abled brother, and a four-year-old sister.

The family structure, at least three investigators that HT spoke to said, was convoluted: the father first married 18 years ago, and after struggling to conceive, he married his wife's younger sister 1...