Investigators say Cottard, a Joliette resident, stepped out for air on his lunch but never returned to his downtown workplace, and never came home that night.
The woman is identified as white, in her 20s, with brown hair. Police say she was seen at ComplexeDesjardins, on Ste-Catherine Street West, at around 1:30 p.m. on the same day Cottard disappeared.
She was wearing a pale, fur-lined winter coat at the time.
Police believe she's the last person who saw Cottard before he disappeared.
Anyone with any information about the woman or Cottard's disappearance is asked to phone Info-Crime Montréalat 514 393-1133.