Family members of the 13 year boy Sheikh Samiul Alam Rajon alleged that Rajon had been killed as watchman Moyna Miah failed to ravish him.
Abdul Malek and Omar Faruque, paternal and maternal uncles of Rajon, told a news agency that Moyna wanted to ravish the child, Rajon.
They said as Rajon refused to the proposal of the accused, he was killed bringing the theft allegation against him.
Omar Faruque, said, "Moyna is already accused of questionable character. He killed my nephew as he disagreed with his (Moyna) immoral proposal."
Meanwhile, Kamrul Islam, 24, one of the accused of Rajon murder, was arrested by police of Jeddah in Saudi Arabia on Monday evening, said Mohammad Rahmath Ullah, Additional Deputy-Commissioner of Sylhet Metropolitan Police.
He said they would try to bring back the accused in Bangladesh shortly.
Earlier, Azizur Rahman and Lubna Begum, parents of the victim, said that Kamrul Islam fled to Saudi Arabia soon after the incident to avert arrest.
But the police official differed with them, saying that they sent a letter to the immigration police so that Kamrul could not flee the country.
Meanwhile, quoting from autopsy report, the Officer-in-Charge (OC) of Jalalabad Police Station Akhtar Hossain said that the death of the victim was caused by brain haemorrhage and around 64 injury marks were found on his body.
Tasmina Islam, a doctor at Osmani Medical College and Hospital, performed the autopsy of the victim and handed the report to the police.
Police on Monday arrested Ismail Hossain, 30, and Lipi Begum, wife of another accused Muhith, in this connection.
Alamgir Hossain, investigation officer of the case, produced Ismail Hossain before Magistrate Court-2 in Sylhet praying for a seven-day remand. The court fixed today (Tuesday) for hearing the remand prayer. A Sylhet court on Monday placed Muhit Alam, who was arrested soon after the death of Rajon, on a five-day remand.
Rajon was tortured to death by a group of people on a theft charge in the Kumargaon Bus Stand area of Sylhet on July 8. One of them even filmed the horrendous scene to share it on Facebook.
After the killing, the culprits were taking his body on a microbus to dump it in a secluded place, some 200 yards from the torture spot.
They caught attention of some locals. Chased, three of the group fled but Muhit was caught. He was handed over to police.
Jalalabad police filed the murder case accusing Muhit and his brother Kamrul Islam, 24, their accomplice Ali Haider, 34, and watchman Moyna Mia alias Boro Moyna, 45.
State Minister for Home Affairs Asaduzzaman Khan Kamal said, "None would be spared of Rajon killing".
"The incident is tragic and pathetic. None will be spared. All the accused will be brought to book," the minister said at his office.
On Monday, many political and social organisations held various protest programmes demanding punishment to the killers of Rajon.