Maharashtra Anti-Terrorism Squad (ATS) filed a charge sheet against city-based engineer Anees Ansari, arrested in October last year for allegedly conspiring to blow up a US establishment in the city, in a magistrate's court in Mumbai on Wednesday.
"We have filed a 728-page chargesheet against Ansari and the wanted accused Omar Ejaj," said a senior ATS officer.
It contains statements of 50 witnesses including the forensic experts who submitted a 40-page report of examination of six computer hard disks and a mobile phone seized from Ansari.
According to ATS, Ansari was a sympathiser of the Middle-East terror group Islamic State of Iraq and Syria (ISIS).
His online chats hinted at a plot to target US establishments including a school in suburban Bandra, it says.
He has been booked under section 302 (murder) of Indian Penal Code and relevant sections of Information Technology Act.
Ansari, a resident of suburban Kurla, had also applied for a passport a month before the arrest, which led the investigators to suspect that he was planning to leave the country to join the ISIS.