The incident took place after police personnel of Bazarpeth police station under Kalyan division in Thane nabbed an alleged accused in a rape and extortion case and took him to the police station, police said.
The couple followed them to the police station and created nuisance, they said.
The police said a Mr Milind Daund, who was booked in the criminal case, was detained for interrogation.
A complaint against the couple was filed by police constable Ms Sunita Dighe, who in her complaint described the entire incident which took place at the police station for well over an hour late last evening.
In her complaint Ms Dighe named the couple who had created the nuisance as Ms Neelam Pawar (26) (sister of the nabbed accused) and Mr Pratik Ravindra Thackery (23).
While the police held Mr Pratik, the woman escaped from the police station and the cops are now looking for her, police said.