Dr Michael Pollanen, one of the three foreign experts who reviewed the Jamaican post-mortem of Woolmer, said that a "foreign substance or toxin" was found in the former England player's system.
Dr Pollanen told the ongoing inquest in Jamaica yesterday that he was not even given a toxicology report, the Mirror reported.
When Jamaica's Director of Public Prosecutions Kent Pantry asked: "Were you informed that poison was in his stomach?" Dr Pollanen said: "No. I am aware that there is a positive toxicological finding ... a foreign substance or toxin was detected."
An inquest into the mysterious death of Woolmer began in Jamaica last week with a British pathologist telling a Jamaican court that he found no marks of strangulation on the coach's body.
Contradicting the claims of the Jamaican police, which clung for three months to the theory that Woolmer was throttled in a Kingston hotel room, Dr Nathaniel Cory was quoted by The Telegraph as saying: "If I was asked if there was a violent struggle, I would say 'No'."
Bernice Robinson, a Jamaican hotel maid, however, told the 11-member jury at the inquest in Kingston how she found Woolmer's body in a dishevelled, blood-spattered room on the day after his team was knocked out of the 2007 World Cup by Ireland.
Robinson said that she noticed an overturned chair and blood on the pillow. Besides, there was a smell like a mixture of alcohol and vomit when she entered the room to clean it on the morning of March 18.
She then saw a man's leg sticking out of a bathroom door, but she could not open it because 58-year-old Woolmer's body was blocking it from the inside.
Robinson said that before entering the room with a master key, she had knocked on the door of the room at the Pegasus Hotel earlier in the morning.
Another maid was called in, and both of them together could not open the door. It was then that they called for more help.
Despite claims that a killer would have found it next to impossible to extricate himself from the tiny bathroom while leaving his victim slumped against the other side of the door, police refused to confirm how Woolmer was found and pushed ahead with a murder investigation.
Acting on autopsy findings, Jamaica police initially said that Woolmer had been murdered. It was an announcement that sparked media frenzy about a possible link to match fixing.
But after months of investigation and a re-examination of autopsy results, the police eventually backtracked, saying Woolmer had died of natural causes, probably heart failure.
Three foreign experts reviewed the Jamaican post-mortem, after which police said it were natural causes and toxicology tests were negative