A man killed in a downtown stabbing has been identified as a cancer research scientist.

Mark Ernsting, 39, was fatally wounded outside of a home on McGill Street, in the area of Yonge and Gerrard Streets, at approximately 9:30 p.m. on Tuesday.

Emergency crews were called to the scene, where they found a man in life-threatening condition. He was rushed to hospital, where he was pronounced dead.

Ernsting has been identified as a biomedical engineer who worked at the Ontario Institute for Cancer Research.

The victim, who was also an adjunct professor at Ryerson University, was out for his usual evening walk when he was approached by a man and fatally stabbed, police say.

Investigators believe the stabbing was the result of a botched robbery.

"We are deeply saddened at the passing of Mark Ernsting – a talented researcher and terrific person," the OICR posted on Twitter Wednesday.

"Our thoughts are with his loved ones."

Friends and colleagues gathered at the scene on Wednesday to remember Ernsting.

“It’s not the first time we have seen police tape across the street before, but this is just crazy what’s happened here,” said Elaine Wilson, one of the victim’s friends. ‘

Toronto Mayor John Tory, who also visited the scene, expressed his shock over Ernsting’s death.

“It’s quite different than these kind of targeted executions we see elsewhere which are a problem and are also unacceptable, but this is something that people just don’t expect to have happen in the city,” he said.

About two hours before Ernsting was killed, a woman was stabbed during a street robbery in the area of Yonge Street and Summerhill Avenue.

Police believe the same attacker took the subway to McGill Street and stabbed Ernsting.

A suspect was later arrested near the scene of the first attack.

Calvin Michael Nimoh, 21, has been charged with second-degree murder. He has not been charged in connection with the first stabbing.

Nimoh appeared in court on Wednesday.

The investigation is ongoing.

With a report from CTV Toronto’s Tamara Cherry