DHAKA: Bangladesh police said Thursday they had arrested a man on suspicion of filming the brutal murder of a 13-year-old boy that provoked public outrage after the footage went viral.

Police arrested Nur Mia, 20, on the outskirts of the north-eastern city of Sylhet late Wednesday.

“Nur Mia shot the video on his Nokia set at the instruction of Kamrul (Islam),” local police chief Akhter Hossain told AFP, referring to another suspect in the case.

“He then uploaded the video to Facebook and shared it with his friends, “said Hossain.

Read: Bangladesh lynching anger grows as suspect confesses

Mia is the ninth person to be arrested over the July 8 killing of Samiul, who was tied to a pole and then subjected to a brutal assault in which he pleaded for his life.

Islam fled to Jeddah in the immediate aftermath of the attack but reports said he had been arrested by Saudi authorities.

Police said Wednesday they had arrested another man, Moyna Chowkidar, calling him a “prime” suspect.

The 28-minute video of Samiul, which was widely circulated after being posted on social media, has prompted deep soul-searching among Bangladeshis as well as a series of protests.

Thousands of people demonstrated in Samiul's home city and across the country for days, demanding that the killers be sent to the gallows.

Bangladesh authorities have promised swift action against the killers, who had accused Samiul of stealing a bicycle.

His family says he was innocent and police said their investigation had found “no evidence of theft”.

In the video, the terrified youngster can be heard screaming in pain and repeating: “Please don't beat me like this, I will die.“

At one stage he is told to walk away. But as he tries to get to his feet, one of the attackers shouts: “His bones are okay. Beat him some more."