Police in Cumilla have arrested a fourth suspect in the murder of 13-year-old Ishayat Shahriar Oprotim, accusing him of concealing what he knew about the killing while saying he took no direct part in it.

Md Siam, 19, was shown arrested in the case and produced before a Cumilla court on Monday morning. He lives in the Sudhanyapur (Noabari) area under Cumilla Sadar South Model police station.

Asaduzzaman, superintendent of police for Cumilla, said Siam had not taken part in the killing itself.

According to police, Saiful Islam, known as Tuhin and described by police as the main figure behind the killing, spent about 90 minutes with Siam on Friday evening after the murder and told him in detail what had happened. Siam kept the information to himself, was detained as a suspect and was subsequently shown arrested in the case.

Lutfor Rahman, additional superintendent of police and media officer for Cumilla district police, said Siam was questioned on Sunday night and sent to court at about 11 am on Monday after information obtained during the questioning confirmed the matter.

All four accused have been handed over to Cumilla jail authorities; the two adults will remain at the jail, according to Md Rakibul Islam, officer-in-charge of Cumilla Sadar South police station. Two juveniles directly involved in the killing were sent to the Tongi Child Development Centre in Gazipur on the court’s orders, police said.

Oprotim went missing on Friday after leaving a rented house in the Gandhamati area of Kotbari in Cumilla. His body was recovered at noon the following day from a woodland on the Lalmai hills in Sananda village, Bijoypur union, Sadar South upazila.