His body lies on the bank of a river with his legs still in the water; barely moving.

A man bends forward to check if he is alive. Another pokes the body with a stick.

"Is he responding?" asks the first man.

"Yes," comes the reply.

The first man then kicks the body, already stripped to only what seems like his undergarment and a vest, and kicks again until the skinny body rolls into the river.

Already drained out of energy, he gasps for breath; faintly.

The torturers then pull him ashore again with a rope that is tied to his left wrist.

Now two men press burning cigarettes on his face to see if he is still alive while another hits him with a stick.

"Water ... water!" the boy groans weakly.

"Water? There's a lot of water down there," says the man with the stick, pointing to the river. "Go now and drink as much as you like."

Then the first man again kicks the body back into the water.

His head barely above the water, the boy feebly opens his mouth for more air but water, dirty and stinky, seeps through.

Crowds on the shore keep jeering at him and cursing him.

"Why can't he die?" says one.

"Say your last prayers to God ... And die!" says the other.

The boy makes one last frantic effort to move out of the water but fails.

The mob bursts into barbaric laughter at this. Some even clap in a sick display of what man is capable of.

This is no scene from some horror film; nor is it a work of fiction. It is all so real as it can be.

This is exactly how Najim Uddin, 16, was killed by a mob in the capital's Khilkhet area on April 13. He was the son of local vegetable vendor Jalal Uddin from Mastul village.

What was Najim's crime? He allegedly had stolen a pigeon from a neighbour's house.

This gruesome incident was videotaped and The Daily Star has obtained one of the clips.

Though he was alive till the end of the 5:39 minute long footage, he was later killed and his body was dumped in the nearby Balu river.

However, the family came to know about this incident not until April 17 when a neighbour, who claimed to have witnessed the incident, told them.

"I was told by locals that they started torturing my son from 3:00am and went on for six hours," Jalal told the Daily Star.

He filed a case with Khilkhet Police Station that very day.

Najim's body, meanwhile, was found in the Shitalakkhya river at Noapara of Rupganj in Narayanganj on April 16.

"The body was sent for an autopsy and later buried as an unidentified body," said Officer-in-Charge Jahirul Islam of Rupganj Police Station.

They had notified other police stations and sent a photo of the body.

Najim's parents saw the photo at Khilkhet Police Station and went to Rupganj to claim the body.

"To ascertain their claim, we collected DNA samples from the grave and sent those to the CID [Criminal Investigation Department] for screening," the OC said, adding that they hadn't got the test result and the victim's family was yet to get the body even though more than three months had passed since then.

After Jalal filed the case on April 17, Khilkhet police had arrested three people, including witness Rajan. But none of them were seen taking part in the savagery.

So where are the real killers?

"The killers seen in the video have fled the area. We are trying to track them down," said Inspector Gholam Faruq of the Criminal Investigation Department. He is investigating the case.

Meanwhile, unhappy with the probe progress, the CID on Wednesday formed a three-member committee led by an assistant superintendent of police, said Special Superintendent of Police Mirza Abdullahel Baqui.

"We will scrutinise the process of investigation. If we find a lack of sincerity in the investigation, we will take actions against the official concerned," he added.

In a similar incident of savagery, a mob beat Samiul Islam Rajan, 13, to death in Sylhet on July 8 for "trying to steal a rickshaw".