Claude Létourneau, the man charged with hiding bloody needles in clothes at Quebec retail stores, pleaded not guilty at the Sherbrooke courthouse on Friday morning.
Létourneau, 49, was charged with 29 counts of armed assault, after DNA evidence lifted from the syringes linked him to the incidents.
"It is with pride and relief that we are happy to announce this arrest," said Gaétan Labbé, director of the Sherbrooke police department.
Eight people have pricked themselves with the syringes and have undergone testing to ensure they were free of infections. They are awaiting test results.
Twenty-five needles have been found since January.
The last needle was found on May 24 at The Bay in Carrefour de l'Estrie, a shopping centre in Quebec's Eastern Townships.
Police said the suspect was arrested Thursday morning, the second time authorities have picked him up in the last two weeks.
He was arrested earlier for uttering threats to a co-worker.
Police said he is known to authorities.
Police say they discovered a link between Létourneau and a case of bloody needles in Lévis in 2002.
He is undergoing a psychiatric evaluation.
Létourneau will remain in custody until his next court appearance, on June 14.
The City of Sherbrooke and its police force had offered a $5,000 reward for information in the case.