Turkish man being transferred to prison under police guard has escaped by jumping from a passenger ferry into the Aegean Sea, officials said.
A major search-and-rescue operation is underway for the man, who was handcuffed when he leapt overboard near the island of Chios.
A prosecutor has ordered the arrest of the four police officers who were escorting the prisoner pending an internal investigation into the security breach.
The man was being transported by ferry from Mytilene to Korydallos prison in Athens when he made his escape in the waters between Chios and the Oinousses islands.
According to reports, he was sleeping on the ferry floor when a passenger opened a door to an outside deck.
The detainee reportedly took advantage of the moment, running past his guards and leaping into the sea.
Passengers filmed the incident and tried to keep a spotlight on the man in the water, but he disappeared after several hours.
The escaped man was first arrested on July 7 by the coast guard on suspicion of migrant smuggling.