Shields said police were yet to make a significant breakthrough and were anxious to hear from anyone who had been at Kingston's Jamaica Pegasus hotel in the 72 hours preceding the discovery of Woolmer's body.
"What I need to do is to identify everybody in the hotel from Friday through to Sunday when Bob's body was found, in an effort to establish everybody's movements during that period of time," Shields told reporters.
"Not just as suspects but as potential witnesses - people who may have heard something, seen something within the hotel that raised their suspicions, that so far they haven't come forward with.
"The important thing is that we get to those people and give them an opportunity to come forward and talk to us," Shields said.
"Nothing can be overlooked in a case like this."
Shields urged any cricket fans or tourists who had since returned from the cricket World Cup to dial the international hotline (+1-876-927-5000) or contact their local police.
"You can call the number 24/7 to give information.
"If you don't want to call internationally, call your local police if you're now back at home in your own country," he said.
Ongoing investigations
Woolmer's naked body was found in his room at the hotel after Pakistan were eliminated from the World Cup after just two matches, following a defeat to the West Indies and a shock loss to debutants Ireland.
The 58-year-old former England international's killing has been linked to match-fixing although Shields has repeatedly stressed investigators are keeping all lines of enquiry open.
Meanwhile Shields said investigators would not rush the result of toxicology tests carried out on Woolmer's body, which have been ongoing for over a week.
"I spoke to the leader of the forensic laboratory this morning," Shields said.
"She assured me she will work as quickly as they can. I asked her how long will it take and she answered 'When it's ready.'
"I have to respect their professionalism and wait until they tell me they have the results."