Woolmer, 58, was found dead in his hotel room in Jamaica on March 18, the day after Ireland surprisingly defeated Pakistan and sent them crashing out of the World Cup tournament.
Days after his death police announced they were treating the case as a homicide, saying an autopsy report showed he had been strangled, sparking feverish speculation about the role of bookie mafias in the game.
But after three independent pathologists' reports, a barrage of toxicology tests and interviews with hundreds of people, police Tuesday ruled out any foul play or match-fixing in the death of the former England Test player.
"Mr Woolmer died of natural causes," Jamaica Constabulary Force (JCF) commissioner Lucius Thomas said, referring to a finding by a British forensics expert that was supported by South African and Canadian pathologists.
"The JCF accepts these findings and has now closed its investigation into the death of Mr Bob Woolmer," Thomas said, adding toxicology tests had also ruled out another earlier theory that Woolmer had been poisoned.
Neither Jamaican police nor the International Cricket Council (ICC) "have found any evidence of any impropriety by players, match officials nor management during the investigation of Bob Woolmer's death," Thomas added.
Police interviewed some 400 people and took statements from 250 others. Detectives from Scotland Yard and Pakistan were also involved in the inquiry.
"We are relieved that it has been officially announced that Bob died of natural causes," Woolmer's widow, Gill, told AFP from her home in Cape Town, South Africa. "It is now over."
Woolmer suffered from diabetes. According to reports in Jamaica last month Scotland Yard detectives had determined that the British coach had died of a heart attack.
The head of the ICC's corruption-busting force said those who linked Woolmer's death to match-fixing rumors should now "shut up."
The reputation of both the World Cup and the game were "unnecessarily tarnished as the theories about Woolmer's death became wilder and more bizarre with many of those theories suggesting a link to corruption and match-fixing," said Paul Condon, chairman of the cricket body's Anti-Corruption and Security Unit (ACSU).
"To those who suggest that corruption is still widespread throughout the game of cricket ... we have one clear message: put up or shut up," Condon added in a statement posted on the ICC website.
Pakistani players said they were relieved at the news, but some were angry enough to call for the Caribbean investigators to be sued.
The entire Pakistan squad was fingerprinted and ordered to provide DNA samples following Woolmer's death.
An initial autopsy report after Woolmer's death proved inconclusive, but a pathology report some days later indicated he died of asphyxia as a result of "manual strangulation," which had led police to treat his death as murder.
Then-Pakistani captain Inzamam-ul-Haq -- one of three squad members who were questioned twice after police alleged Woolmer was strangled -- said however there was no need to reopen wounds with legal action.
"I don't feel court action would be of any use now. The players in general and I, as captain in particular, went through hell and those were the most terrible days of our lives," Inzamam told AFP.
Jamaican police sought Tuesday to defend themselves against accusations of incompetence, saying they had only sought to be thorough.
"This was an extraordinary case," said Thomas's deputy commissioner Mark Shields, a former Scotland Yard officer from Britain.
"Murder investigations are not like TV series, where everything is wrapped up in 45 minutes. All we could do was conduct a thorough investigation and not rush."
The force "adopted a thoroughly professional investigation where nothing was left to chance. Every effort has been made by the Jamaica Constabulary Force to seek the truth surrounding Bob Woolmer's death," added Thomas.
Woolmer, who made his home in South Africa, was cremated at a private family ceremony in Cape Town on May 4.