An employee of an advertising firm was found dead in his workplace in the capital's Niketan area yesterday evening, hours after an unknown caller had demanded ransom from his family.

The body of Rezaul Hossain Shakil, 25, was lying on the floor of the store room of  ad firm Tinsel Town, said police.

Shakil worked as an office assistant at the firm on the first floor of a multi-storey building on Road-3 of Block-B in the area.

Talking to The Daily Star, Gulshan Police Station Officer-in-Charge Abu Bakar Siddique said there was a “black mark” on Shakil's neck.

They did not find his mobile phone, he added.

From Shakil's cellphone number, someone had called his father Nur Nabi in the morning, demanding ransom, the OC quoted the father as saying.

The police official did not mention the  ransom amount. But the victim's colleague Mosharraf said the amount was Tk 2 lakh.

Shakil used to stay inside the office overnight and was doing so on Monday too, said the OC, quoting the victim's colleagues.

Other employees of the firm found the door of the store room locked from the outside on Tuesday morning. First they thought Shakil went somewhere.

After a while, they broke open the door and noticed the body.

Rafiqul Islam, assistant commissioner of Dhaka Metropolitan Police (Gulshan Zone), said they detained a man named Arafat.

During primary interrogation, Arafat, a worker at a nearby workshop, confessed to killing Shakil following a dispute over money and drugs, he said.

They were investigating the incident, said the police official.

The body was sent to Dhaka Medical College morgue for autopsy at midnight.