Sherbrooke's police chief is urging people not to panic as more dirty needles turn up tucked into pockets of clothes on display in the city's shopping areas.

However, Chief Gaétan Labbé is telling shoppers to be cautious.

"We have a sick person who is in the Sherbrooke area right now who is creating a certain amount of panic in all the shopping centres," he said.

"I think it's premature to tell citizens to stay at home. What is important to remember is we have police officers patrolling inside shopping centres . . . The most significant caution is for the men and women working inside these shopping centres."

Twenty syringes containing a small amount of blood have been found needle side up in the pockets of pants and shorts in a number of stores in the city since January 20. The latest syringe was discovered on the weekend.

At least eight people have been injured after sticking themselves with the needles while handling the clothes.

Labbé addressed the media in Sherbooke today and called for calm vigilance in the face of the ongoing needle incidents.

He said the file is a priority for investigators and they have a two officers and dedicated laboratory resource in Montreal handling the case.

No suspects identified

While officials have confirmed the DNA found on the last three needles discovered belongs to the same person, no suspect has been identified and there was no match in the police database. They're still working on the other files.

Investigators are working with provincial police to develop a profile of the suspect. They’re also working through tips and leads that have come in from the public.

Labbé said it’s very difficult to say if a sole person is behind all of the needles.

"It could be one person who puts the [syringes] in the different clothes in the different stores and it could be the blood of another person," he said.

"So, can we make a link between the person who is placing the syringes and the blood inside, at the moment we can’t say."

Patrols increased

Police have upped patrols in local shopping areas for security and to inform people about the incidents. There are security cameras in certain stores and that tape is being reviewed, Labbé said.

Those pricked by the needles are undergoing testing to ensure any diseases have not infected them.

Labbé said people should be prudent and take the time to look at the clothes before they try them or put their hands in pockets.

"It really is just caution," he said. "We can’t give any other advice right now."