Montreal police have released a sketch of a man they are calling "an important witness" to the assault and robbery of a 74-year-old woman.

Police spokesperson Andre Leclerc said the man has a distinctive appearance.

"This young man, early 20s, described as quite tall -- to six feet -- slim, a black person with light skin, light blue colour eyes, and he had dreadlocks," said Leclerc.

Faigie Adelman was beaten with a baseball bat soon after driving into her parking garage at 6000-6010 Cavendish Blvd. in Cote St. Luc on Tuesday.

Surveillance video showed a man running through the automatic garage door before it closed, and minutes later showed that same man running away while rifling through her purse, but did not capture the attack itself.

Police can't yet say that it was a targeted attack or if Adelman knows her attacker.

But some residents pointed out her attacker seemed to know the building. They have key fobs to get into the garage.

“What I understand now is that there's a stairwell to get out if there's a fire, so he obviously knew how to get out, so obviously he knew something about the building,” said one woman.

It’s information like that police were after when they set up a command post outside the building Friday and spoke to residents inside the building.

“Any kind of little details could be major for us,” said Leclerc.

Adelman was placed in a medically-induced coma following the assault and remains in critical condition, although doctors expect she will survive.

Police believe they'll be able to piece together why this attack happened once they find the witness.