Police yesterday arrested the prime accused in a case filed over the murder of a youth, Md Arafat, in Mohora area of Chittagong on Monday.

The arrestee is Md Arman, 20, a guard of a gymnasium in the area.

Police arrested him in Kalurghat area around 4:30am, said Bashir Ahmed, officer-in-charge of Chandgaon Police Station. “Police also recovered the knife used in the murder,” he said.

On Monday, Arafat, 19, was stabbed to death allegedly by Arman and his accomplices over an altercation they had the night before.

Arafat, who worked at a welding shop, used to go to “Popular Gymnasium” for exercise, said the OC. On Sunday evening, he went there and found that the gates were locked. So he “rebuked” the guard, Arman.

“They also had an altercation,” said the OC.

The next night when Arafat got out of the gym after a workout around 9:00pm, Arman and his accomplices stabbed him and fled the scene, he added. Arafat was declared dead at Chittagong Medical College Hospital.

His mother filed a murder case accusing Arman and some others. Earlier, police arrested two persons. Gleaning information from them, police arrested Arman, said the OC.