Pakistan's final match at the World Cup began today with a minute's silence and a rush of disbelief and rumour as police in Jamaica said they were treating the death of Bob Woolmer, the team coach, as suspicious.

Woolmer was found unconscious in his hotel room on Sunday morning and was pronounced dead after being transferred to hospital. The 58-year-old's team had suffered a stunning defeat to Ireland the previous day which ended their chances of reaching the next stage of the tournament in the West Indies.

In the hours after his death, the Pakistan team management revealed that Woolmer, a former England test all-rounder, had been suffering from diabetes and his wife, Gill, said that he had been experiencing intense stress.

But late last night, Mark Shields, the Jamaica's deputy police commissioner and former Scotland Yard detective, read a brief statement which said: "At the press conference earlier today we reported that the cause of death was inconclusive.

"Having met with the pathologist, other medical personnel and investigators there is now sufficient information to continue a full investigation into the circumstances surrounding the death of Mr Woolmer, which we are now treating as suspicious.

"We have already informed the Woolmer family of this development and we are also in close contact with the Pakistan team management, Cricket World Cup and ICC to ensure all parties are kept informed of the ongoing investigation."

This morning, Mr Shields, a former leading detective in Scotland Yard's Serious and Organised Crime Squad, repeated that "there is no evidence it’s a homicide" but a team of 12 forensic crime officers descended on Woolmer's room at the Pegasus Hotel in Kingston, where the coach was found by a member of staff at 10.30am on Sunday.

At the same time, Pakistan prepared to play Zimbabwe in their final match of the tournament, where the team spoke of their shock and determination to win the game for Woolmer's memory.

"This is a tough time for us because the coach is not here," said Inzamam-ul-Haq, the Pakistan captain, who has announced his intention to retire from one day cricket after the tournament.

"The incident has disturbed the whole team also but we’ll play our level best. We’ll try to win this game on Bob Woolmer’s account," said Haq, before winning the toss and choosing to bat.

As Pakistan began their final game, former players and team officials aired conspiracy theories about the possible reasons behind Woolmer's death.

Sarfraz Nawaz, the former Pakistan fast-bowler, said he believed the former Warwickshire coach was murdered. "Woolmer’s death has some connection with the match-fixing mafia," Nawaz told the Associated Press. "I’ve been saying this for the last four days that Woolmer’s death is not natural, but it’s a murder."

The team's media manager, Pervez Mir, who told journalists on Sunday that vomit and blood had been found in Woolmer's room, said: "Obviously ’suspicious’ could be anything at this moment. It could be something serious, it could be something not serious. We have a man who is down and we don’t know the reason why."

Gill Woolmer, the coach's widow, said that she had received an e-mail from her husband after the disastrous defeat to Ireland and that she had no reason to suspect foul play.

"I don’t see any conspiracy in his death," Mrs Woolmer told an Indian television news channel this evening. "He had nothing to do with the match-fixing controversy and any such person being involved is highly unlikely. We never got any threats as far as I know."

"I didn’t speak to him after the match but he emailed me the following morning," she told the NDTV India. "He did mention that he was really depressed and could not believe how this could have happened. We discussed some personal issues apart from this."

In Pakistan, Imran Khan, the former captain who led his country to victory in the World Cup in 1992 urged the Jamaican police to deliver a final answer.

"We really need to know what is behind it. I think they have to get to the bottom," he said. "This just adds to the whole tragedy and especially for Bob’s family. I still assume he died of natural causes because he was a diabetic and that is closely associated with heart attacks."

Meanwhile Derek Underwood, president of Kent County Cricket Club and a former Kent and England team-mate of Woolmer, said: "I and you and everyone are waiting anxiously for further news. That’s all I can possibly say."

After today's match, Pakistan will hold a remembrance ceremony at their hotel before going to Montego Bay for a two-day break at the invitation of Portia Simpson-Miller, the Jamaican Prime Minister, on their way home.