Pakistan's cricket coach Bob Woolmer was murdered in his hotel room on Sunday after the team's World Cup shock defeat to Ireland, Jamaican police say.
It is now known that Bob Woolmer was strangled
A post-mortem examination established that the former England player had died as a result of "manual strangulation", police commissioner Lucius Thomas said.
"In these circumstances, the matter of Mr Woolmer's death is now being treated as murder," he told a news conference.
Police say Mr Woolmer may have known his killer or killers.
The 58-year-old was found unconscious by staff at the Pegasus Hotel in Kingston on Sunday morning.
Police said there were no signs of forced entry into his room and none of his possessions had been taken. Authorities are studying CCTV footage from the hotel.
The deputy commissioner of the Jamaican police, Mark Shields, said this might now be a hunt for more than one killer, and urged the perpetrators to hand themselves in.
"Bob was a large man. It would have taken some significant force to subdue him," he said, adding that police were ruling nothing out and had "lots of lines of inquiry".
"I have to say at this stage that it looks as if it may be somebody who's somehow linked to him, because clearly he let somebody into his hotel room and it may be that he knew who that person was," Mr Shields told the BBC.
Mr Shields also "unequivocally dismissed" Indian television reports that arrests had been made.
"That's nonsense, as far as I'm concerned. There's actually no truth in that," he said.
The BBC's Andy Gallacher in Kingston says that Bob Woolmer's murder has stunned the cricketing world and left the World Cup in disarray.
Speculation that this may be connected to gambling cartels is only adding to the confusion surrounding his tragic death, our correspondent says.
On Thursday, Jamaican police questioned members of Pakistan's cricket squad over the death.
After being interviewed for about an hour and fingerprinted, the team left for the resort of Montego Bay.
Woolmer's death has cast a long shadow over the World Cup
They are planning to return to Pakistan on Saturday.
Pakistan team spokesman Pervez Jamil Mir said the players were "in a state of shock" over the news that Mr Woolmer had been killed.
However, the sport's governing body, the International Cricket Council (ICC), said the competition would continue as planned to "demonstrate that cricket cannot be put off by a cowardly criminal act".
ICC chief executive Malcolm Speed said the entire cricket community was shocked by the death of the former England Test batsman and South Africa coach.
He said: "Everyone connected with this event will assist the police in any way possible to ensure the truth emerges."
During his career, Woolmer also coached South Africa and enjoyed great success coaching in English county cricket, winning four trophies in two seasons with Warwickshire.