The trio were held when the police was maintaining a vigil at casinos in view of the assembly bypolls.
The Goa Police and Income Tax department are questioning a casino owner after three persons were nabbed in Panaji last week with Rs 15 lakh cash. The trio were held by the police who were maintaining a vigil at casinos in view of the assembly bypoll for Panaji seat, which was held on Wednesday.
Chief Minister Manohar Parrikar is pitted against the Congress' Girish Chodankar in the bypoll.
"Three Hyderabad-based youths were apprehended during patrolling on the intervening night of August 14-15. They were found to be carrying Rs 15 lakh cash in their car," Superintendent of Police (North) Chandran Chaudhary told reporters.
The trio claimed they had earned the money during their visit to a casino in Panaji, the officer said, adding that Income Tax department began its probe after it was informed about the seizure of cash.
Mr Chaudhary said owner of the casino is being questioned jointly by the police and IT sleuths.
Meanwhile, the police in Valpoi constituency have registered an FIR against Congress leader and Ponda MLA Ravi Naik, whose son Roy is the party candidate for Wednesday's bypoll against BJP's Vishwajeet Rane.
Mr Naik was booked under section 188 (disobedience to order duly promulgated by public servant) of the IPC after he was found moving around in a vehicle in the constituency last night, Mr Chaudhary said.
The officer said nothing objectionable was found in the vehicle of Mr Naik, but as per the Election Commission guidelines the star campaigner cannot remain in the constituency he does not belong to, 48 hours prior to voting.
Mr Naik lives in Ponda.