It's believed that Danny Kelly, the amateur rugby player from Haworth, may have been assaulted before dying on holiday in Greece this week.
Police in Greece have launched an investigation into the death of the 23-year-old, who died on Monday on the Greek island of Zakynthos.
Representatives of the family say it is understood that Mr Kelly was the victim of a serious assault and had fled into the sea.
Investigations are still at an early stage. It's understood there may be a second post mortem once Kelly's body is returned to the UK.
A family who've waited five years for answers about their son's death asked again today for the government to help. Matthew Cryer from Killamarsh died on the Mediterranean island of Zante in 2008 - he was only 17 and on holiday for the first time without his parents.
The Greek police have promised to investigate but the case keeps stalling. Today Matthew's family went to the Foreign Office to push for progress.
The father of Matthew Cryer, the teenager killed in Zante, is expecting to fly out this week to give evidence in the trial of the men accused of killing his son.
The father of a teenager from Killamarsh near Sheffield who was killed on holiday in Greece is set to appear at his murder trial. 17 year old Matthew Cryer died from head injuries in 2008 outside a bar in Zante.
At an inquest in Chesterfield in 2009 witnesses said they saw him being thrown into the street. Earlier this month Greek police re-opened the case. Matthew's father, David, has been summoned to the trial of the men accused of killing his son.