Apart from the hotel owner, the detained persons include a group of contract killers, who allegedly shot dead M M Khan, an assistant legal advisor with the NDMC, police said.
Khan was allegedly shot dead at a crowded street on Monday evening when he was heading back home in his car which was intercepted by motorcycle-borne assailants, who shot at him from a close range.
The hotel owner was allegedly pressurising Khan to waive off penalty worth hundreds of crores due to NDMC, imposed on the hotel on several grounds.
His relatives told police that he had been receiving calls from unknown people during odd hours of the day. Police had recovered his mobile phone and the call data was being analysed, an official had said.