Officers from Cleveland Police's homicide team are investigating after a man died after falling overboard from a transfer vessel into the North Sea.
The incident happened around 2:05pm on Monday 26 September, as the man attempted to move between vessels.
He was rescued from the water by his fellow crew members who performed casualty care until the emergency services arrived.
The man was pronounced dead a short time afterwards.
Homicide detectives and a major enquiry team are investigating the circumstances surrounding the incident, a post-mortem is set to take place to establish the cause of death.
A North East Ambulance Service spokesperson said: "We were called at 2:16pm yesterday to assist the RNLI with a rescued patient arriving back at the lifeboat station in Hartlepool. We dispatched the air ambulance, a paramedic crew and a clinical team leader."
When contacted by Teesside Live, a spokesperson from Cleveland Police said: "Just after 2:30pm yesterday police received a report that a crew member from a ship registered overseas had fallen into the water at Hartlepool whilst moving between vessels.
"He was brought out of the water by colleagues and assisted by the RNLI then treated at the scene by paramedics, but very sadly he was pronounced deceased a short time afterwards.
"Detectives from the Homicide and Major Enquiry Team are continuing enquiries in conjunction with other specialist agencies to establish the circumstances of this incident. A post-mortem examination will take place in due course to ascertain the cause of the man's death.
"Our thoughts remain with his family and colleagues at this difficult time."
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