There are fears that alleged loyalist paramilitary involvement in the murder of Bangor woman Lisa Dorrian may be hampering the police investigation.
Lisa left her handbag and personal belongings behind at a party
The 25-year-old County Down woman has not been seen since leaving a party in Ballyhalbert almost two weeks ago.
Recent reports and graffiti suggest a link between the case and the Loyalist Volunteer Force.
Alliance assembly member Kieran McCarthy said people must not be prevented from helping the police.
"If there were people, and there must be people, that know something, they may well be inclined to not do what would be their duty to report to the police even the slightest bit of information," he said.
"And that is very worrying indeed.
"We have seen what's going on in recent times in Belfast in the Robert McCartney case and that's the last thing we would want to find in this case and I hope it doesn't happen."
When she disappeared on 28 February, Lisa, a shop assistant, left her handbag and personal belongings behind her and has not made contact with friends or family since.
Police have said they are treating her disappearance as murder. Her body has not yet been found.
Walls have been daubed with graffiti in the village linking the Loyalist Volunteer Force to her murder.
However, the police said speculation over the case was not helpful and they were concentrating on solid lines of inquiry.
Detectives investigating the murder returned to the caravan park on Saturday to talk to caravan owners and local residents.
A caravan from the site has been removed for examination and a number of premises in Ballyhalbert and elsewhere in County Down were searched last week.
Extensive air and land searches have taken place since her disappearance. Underwater search teams were also used.
Two men questioned about the murder were released without charge on Friday.