Shahinur Rahman, an assistant sub-inspector of Dhaka's Kotwali police station, threatened a plaintiff's wife inside the court premises.
"Have you come here to file a case against the police? The consequences will be disastrous for your family," he said.
The plaintiff Sohel Mir on Monday filed a case at the Dhaka's chief metropolitan magistrate court against five policemen, including Kotwali police station's Officer-in-Charge Mizanur Rahman.
He accused them of extorting money after threatening to put him in "crossfire."
Sohel, a clothing trader, alleged policemen squeezed Tk3.5 lakh out of his family.
He told The Business Standard on Tuesday: "As I went to the court with my wife for filing the case, Shahinur threatened my wife Sabina Abedin. We are feeling insecure after filing the case."
Meanwhile, police claimed that Sohel is a drug peddler and a case was filed against him under the Narcotics Control Act a few years ago.
The trail of the case is ongoing, they said.
Dhaka Metropolitan Police Lalbagh division Deputy Commissioner Biplab Bijoy Talukder told The Business Standard: "A case was filed against him under the Narcotics Control Act. Police are trying to find out more details about him."
"However, we have not yet received any instruction from the court. We will set our next course of action when we get that."
A Kotwali police station official said, "We found a case was filed against him at South Keraniganj police station under the Narcotics Control Act."