PRAYAGRAJ, Sept. 13 -- Cyber fraudsters extorted Rs.7.32 lakh from a teacher in Prayagraj through a 'digital arrest', while three others were duped of Rs.51.91 lakh in separate scams, police said. FIRs were registered in this regard on Thursday. Ramchandra, a teacher from Katra, said he received a call from one Sunil Dutt Dubey, who introduced himself as a DSP, Delhi. Dubey claimed that a case had been registered against him for uploading an objectionable video on social media. On January 17, Dubey threatened to arrest him if he didn't pay up. Ramchandra transferred Rs.7.32 lakh in three instalments. Another teacher, Rajshekhar Shukla of Alopibagh, told police that between early May and June 9, he invested Rs.26.45 lakh in online trading. Meanwhile, a man lost Rs.2.69 lakh in an investment scam while another was duped of Rs.22.77 lakh while trying to consult a doctor....