Montreal police have arrested two suspects but are still looking for a third linked to an abduction case that left a middle-aged woman badly beaten and locked in the trunk of her car on Canada Day.

The two suspects, a 48-year old man and 33-year old woman, were arrested on Wednesday and charged with fraud, after authorities accused them of using stolen credit and bank cards belonging to the victim, Marie-Josée Caron.

"The two suspects apparently used cards, either credit cards or debit cards belonging to the victim," explained police spokesman Laurent Gingras. "These cards were  given to them by the main suspect in this event, Roger Grenier."

Investigators are still searching for Grenier, 53, who faces kidnapping, forcible confinement, robbery, fraud and attempted murder charges in connection to the attack on Caron, Gingras said.

Caron, 56, was robbed and abducted Sunday night near her Outremont townhouse.

Police found her a few hours later locked up in her car suffering severe head wounds.

She was in critical condition in hospital and on a respirator earlier in the week, and police said her chances of making a full recovery are slim.