London - Murdered Pakistan cricket coach Bob Woolmer was poisoned before being strangled, rendering him powerless to fight back against his killer, the BBC will say in a programme on Monday. According to the broadcaster's flagship investigative show Panorama, preliminary drug tests revealed a substance in Woolmer's body that would have weakened him. Woolmer, 58, was found dead in his Kingston hotel room on March 18, the day after cricketing powers Pakistan crashed out of the World Cup in an upset loss to minnows Ireland. The officer leading the investigation, Jamaican Deputy Police Commissioner Mark Shields, told programme makers that it would have been difficult to strangle a man the size of Woolmer, who is six-feet two-inches tall. "It's difficult and it's rare," 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 may be 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." Though the final results of toxicology tests are expected to be handed to Shields and his colleagues next week, they are likely to confirm the preliminary findings, according to Panorama. Woolmer's death led to a fevered round of speculation as to the motive for the murder. The most common theory is that his killing was linked to match-fixing and illegal betting in cricket. Some 30 police investigators are working full-time on the Woolmer case and more than 100 witness statements have been taken. Scotland Yard, Pakistan detectives as well as Interpol have been drafted in to help the investigation.