Investigators have ruled out the possibility of snake venom having been used to kill Pakistan coach Bob Woolmer.
"It is not snake venom," said deputy commissioner of Jamaican police Mark Shields, who is heading the investigation.
Shields went on to add that pathology and toxicology tests have been nearly completed and that the results would be out very soon.
Woolmer was killed in his Kingston hotel room March 18, a day after his side lost to debutants Ireland in the World Cup.
Since then there have been a flurry of unconfirmed media reports from around the world that the former Pakistan coach may have been poisoned by a deadly plant, aconite, or even snake venom before being strangled.
Other reports said the murder was linked to cricket betting, and possible revelations in a book that Woolmer was writing.
Shields also said that the speculation about poisoning was "causing a lot of distress" to Woolmer's family in South Africa.
"The priority is to see the truth. We are seeking experts and taking time to conduct a thorough investigation," Shields was quoted as saying by the BBC.
Shields said that the CCTV footage from Woolmer's Kingston hotel room had been examined and the police had "an array of photographs which may or may not help in the investigation".
He said reports that the footage showed a man leaving Woolmer's room might be wrong, because cameras on that floor were placed in the hall area near the elevator.
Meanwhile, two police officers from Pakistan who went to Jamaica to help the investigators will now be leaving the island after working with local police for three weeks.
"I am leaving the island fully satisfied with the progress of investigations, which are heading in the right direction," said Mir Zubair Mahmood, a deputy inspector general of Pakistan police.
Mahmood clarified that if needed, Pakistani players and officials would travel to Jamaica for further questioning.
Asked whether the incident had anything to do with match fixing and cricket betting, Mahmood said: "Every angle has been looked into."
"Our hope is that we will reach a conclusion on the case as soon as possible," said Jamaica police spokesman Karl Angell.
There has been much speculation in the Caribbean that authorities may not want to divulge details of the investigation and bring in any suspects for fear of spoiling the festival mood around the World Cup.
Some 30 detectives are believed to be working on the case. Four officers from Scotland Yard were in Jamaica to assist in the investigation, following a request from local authorities.