The Royal Newfoundland Constabulary says it arrested a man believed to have used a syringe in three robberies at downtown St. John's convenience stores.

The suspect, 40, is expected to appear in provincial court in St. John's on Tuesday. He faces two charges of armed robbery and a charge of attempted armed robbery.

The RNC said he was apprehended Monday while police were investigating a case of a stolen taxi.

A man used a syringe to rob a convenience store on Queens Road on Sunday evening, and again on Monday morning. Earlier on Monday, a thief tried to rob a store on Hamilton Avenue.

The RNC said it spotted the suspect downtown, and that a police dog tracked him to a small wooded area off Long's Hill.

The RNC said it is continuing its investigation into the stolen taxi, and that the man is also a suspect in that case.