25-year-old Jiah hanged herself at her Juhu residence between 11 PM and 11.30 PM yesterday, sending shock waves in Bollywood.
Jiah, according to police, last spoke to Suraj around 10:40 PM.
Suraj had gone to Juhu police station along with his actor parents and was being questioned, sources said.
According to Jiah's mother Razia Khan, the actress, who made her dream debut opposite Amitabh Bachchan in 'Nishabd', was unhappy about her acting career. She had last appeared in a supporting role in Sajid Khan's multi-starrer comedy 'Housefull' in 2010.
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Khan told the police that Jiah had gone to Hyderabad on June 2 for an audition which did not go well.
Her last rites have not yet been performed because the family is waiting for her friends and relatives to arrive from London, where she was born and brought up.
Police have also questioned her maid, watchman and neighbours to determine the cause of the alleged suicide.
The post-mortem examination at J J hospital suggested the death was caused due to hanging.