East Cyber police on Tuesday registered a case of impersonation, cheating and fraud against an unidentified person who allegedly placed a 69-year-old Mulund resident under “digital arrest” and cheated him of Rs 15 lakh. Between Sept 27 and Oct 14, the scammer contacted the complainant through WhatsApp while he was at his residences in Guhagar, Ratnagiri district, and Mulund (E).