Swedish authorities are weighing charges ranging from drunkenness at sea and gross negligence up to manslaughter after a deadly collision in the early morning hours off the southern coast of Sweden.

Rescue team members quoted in Swedish news reports speak of the collision as a hit-and-run incident.

One crew member is missing after the collision of Scotline's UK-flag 4,800-dwt singledecker Scot Carrier (built 2018) and Rederiet Hoj's 492-dwt Danish-flag cargo ship Karin Hoj (built 1997). One body was found in the capsized Karin Hoj, but has not been identified. The two were the Karin Hoj's full complement.

According to the regional newspaper Sydsvenskan, two crew members from the Scot Carrier were detained on suspicion of the equivalent of "aggravated manslaughter" or "culpable homicide" under Swedish criminal law, but not yet charged.

This comes in addition to previously reported police suspicions of drunkenness at sea and gross negligence.

A statement by Swedish prosecutors describes the detained Scot Carrier crew members as a UK citizen born in 1991 and a Croatian citizen born in 1965.

In its own statement, Scotline Marine Holdings as owners and managers of the Scot Carrier offered their "heartfelt thoughts to the families of the two seafarers" and confirmed that two crew members exceeded legal limits when the ship's crew was tested for drugs and alcohol by Swedish authorities.

The company said it has "a strict drug and alcohol policy in place and have a zero tolerance for any breaches that occur" and pledged to cooperate fully with the investigation.

The Scot Carrier is now alongside at Ystad pending further investigations.

Foggy conditions

The collision took place between Ystad and the Danish-controlled island of Bornholm at a time when the water temperature was about 4C and in fog that may have contributed to the collision.

Swedish national daily Aftonbladet cited rescue operations leader Johan Nilsson as saying the smaller ship bore marks of being run right over.

Scotline said after the collision, "it is understood that the second officer and master of the Scot Carrier were in contact with the Swedish Coast Guard and launched a rescue boat to search for any crew members of the Karin Hoj".

Regional Swedish newspaper Kvallsposten gave an account of the Scot Carrier's movements after the collision based on AIS data plus an interview with an unidentified source who had followed events by radio from the bridge of another vessel at the time of the collision.

After receiving an alarm from the Karin Hoj, Swedish rescue authorities radioed other vessels in the area, and the Scott Carrier responded by saying, "Maybe we have run over something," according to the Kvallposten source. But AIS tracking showed that the ship was in the act of sailing away until Sweden Rescue, the coordinating centre for response operations, called it back.

"It was only after Sweden Rescue ordered, I mean they can't order, but said to them to reverse course that the boat reversed course," said the Kvallsposten source.