The deceased was identified as Rafiq Oishik, 26. Earlier, two more bodies were recovered from Seagull Point of the beach on Friday.
One of the two was later identified as Meher Farabi Avro, 24.
Cox’s Bazar police launched an investigation into the incident when the law enforcement came to know that Avro and Oishik were friends, and belonged to a six-member tourist group that checked in at a local hotel on Thursday.
Their suspicions grew as police could learn that the other four members of the group did not file any complaints or missing person reports regarding Avro and Oishik.
Following this, Cox’s Bazar police detained the four friends on Saturday.
“A group of six checked in at Beach Holiday hotel on Thursday. When two of them disappeared, the other four did not inform anyone. They even kept everyone in the dark when their bodies (Avro and Oishik) were recovered from the beach,” said Cox’s Bazar sadar model police station OC (investigation) Bipul Kanti Dey.
“We find it mysterious,” he added.
The four friends are currently being interrogated at the station, he said.