"But I emphasise once more that we are we are keeping all lines of enquiry open."
Shields's comments followed a report in Britain's Sunday Mirror newspaper that police had received a tip that a cyanide-like poison, aconite, had been used to kill Woolmer, who was found dead at the Pegasus Hotel on March 18 in Kingston.
Aconite causes internal organ failure and forces the victim's breath to slow until it stops.
Death is usually caused by asphyxiation within 30 minutes, the report said.
Shields would not directly comment on the report, but acknowledged police had received information about a possible substance used to knock-out Woolmer.
'Pointless to speculate'
"In the course of our enquiries we have received information about possible poisons that may have been used," he said.
"But until we receive the toxicology reports it is pointless to speculate on what that substance might be."
Woolmer's widow said she was not aware of any claim that her husband had been poisoned.
"I haven't heard anything," Gill Woolmer said from her home in Pinelands in Cape Town, South Africa.
"Everything I know comes from Mark Shields, who said he would keep me informed of any new developments."
The fact that detectives are still awaiting toxicology reports on Woolmer over two weeks after his death has led to questions over whether Jamaica's criminal justice system is capable of handling such a complex murder inquiry.
Bob Woolmer left his mark on
Pakistani cricket [Reuters]
Four police officers from Britain's Scotland Yard are due to arrive in Kingston on Tuesday to review the course of the investigation.
Shields however insisted that the arrival of the officers should not be interpreted as an indicator that the local investigation was floundering.
"This is an entirely standard procedure in any major investigation," Shields said.
"Once you get past the first seven to 14 days of the inquiry it is normal to retrace your steps and make sure nothing has been overlooked."
Detectives were continuing to treat the investigation as murder, Shields said, following press reports in Britain casting doubt on the pathologists' findings which said Woolmer had been "manually strangled".
Woolmer's murder has led to speculation about a possible link to match-fixing in cricket, although detectives have so far said they have uncovered no evidence of corruption.
The Woolmer's death is the subject of the biggest and most complex murder investigation in Jamaica's history, with police revealing they are trying to trace up to 1,000 people as possible witnesses.
In Lahore on Sunday, Inzamam-ul-Haq, Pakistan's captain led a group of seven players among 400 mourners at the 100-year-old Sacred Heart Church, while officials lit candles and laid wreaths at a portrait of Woolmer.