Toronto police are searching for a man caught on camera with a purse belonging to a woman found dead in a downtown stairwell early Sunday.

Surveillance cameras outside the Xerox Centre at Yonge and Bloor streets captured images of the suspect leaving the scene shortly after 33-year-old Bly Markis was killed at bout 10:30 p.m. Saturday night.

The body of Markis, who lived in Toronto, was found by a security guard at about 2 a.m. Sunday in the lower emergency exit to the building at 33 Bloor St. E. One floor below is a TTC subway entrance.

Police said Monday that Markis and her suspected killer entered the building together and were seen walking through the concourse.

"Whether they were acquainted for a long time, we don't know," homicide Det. Chris Buck told reporters at a press conference.

The suspect was captured on cameras exiting the building, but he re-entered a short time later with his hood up over his head and Markis' purse slung over his shoulder.

The man then entered the TTC station and hopped onto a subway train.

"We don't know where he went from that point on, but that is part of our continuing investigation," Buck said.

Police are trying to track Markis' whereabouts before her death. Investigators are appealing for the public's help.

Police have not released the cause of death, but said there was "visible trauma" to Markis' body. No weapon was found.

The suspect is described as a white man with a dark complexion, under 6-feet tall, medium-to-stocky build with a closely shaved head and face.

He was wearing a long, dark hooded jacket and baggy jeans with light-coloured shoes and was carrying a black knapsack with a white Detroit Tigers logo on the back.

Police have not ruled out robbery as a motive.

Buck said Markis did not work in the building where she was found.

The killing is the city's 21st homicide of the year.

An autopsy to determine the exact cause of death is scheduled for Monday afternoon.

A TTC subway station was the scene of two violent attacks earlier this month.

Two men were stabbed, one fatally, at the Kennedy subway station in two separate attacks just days apart.

A 26-year-old man has been charged with second-degree murder in the fatal stabbing.

The incident prompted TTC authorities to review its security measures.

TTC chairman Adam Giambrone says the commission will be installing more cameras and special constables in the coming months.