Pakistan's cricket coach Bob Woolmer, who died of strangulation at the Cricket World Cup, was also poisoned, a BBC Panorama investigation has learned.
The results of toxicology tests mean it now seems certain the ex-England player was rendered helpless before being strangled, according to the programme.
Woolmer's murder in March during the Cricket World Cup in the West Indies cast a shadow over the tournament. His remains were flown back to his home in Cape Town in South Africa on Sunday.
Woolmer was found dead in his Kingston hotel on 18 March, the day after his side lost to Ireland in the World Cup. A post-mortem examination said he had been strangled.
On 20 April the inquest into the death was postponed because the coroner was advised there had been 'recent and significant developments'.
The Panorama investigation learned that a toxicology report on Woolmer's body shows that there was a drug in his body that would have incapacitated him. The final results of the report are due to be given to Jamaican police next week.
According to the BBC website, Panorama's Adam Parsons said: 'Those tests will show there was a drug in his system that would have incapacitated Mr Woolmer. It now seems certain that as he was being strangled, he had already been rendered helpless - leaving him unable to fight back.
'The specific details of that poison are now very likely to offer a significant lead to finding his murderer.'
The policeman leading the murder investigation, Mark Shields, told Panorama that it is 'difficult and it's rare' for one man to strangle another.
Shields said: 'A lot of force would be needed to do that. Bob Woolmer was a large man and that's why one could argue that it was an extremely strong person or maybe more than one person.
'But equally the lack of external injuries suggests that there might be some other factors and that's what we're looking into at the moment.'
Family spokesman Gareth Pyne-James told the Associated Press news agency that Woolmer's funeral in South Africa would be a private ceremony.
