A man accused of killing Ryerson University cancer researcher Mark Ernsting may see his charges upgraded from second- to first-degree murder.

Homicide Det. Paul Worden of the Toronto Police told Metro News that Calvin Michael Nimoh, 21, will be facing the new charges on Jan. 7, the date of his next court appearance.

Ernsting, 39, was walking on McGill St. on Dec. 16 when he was stabbed multiple times by a single assailant around 9:30 p.m. The assailant fled the scene, but was arrested within an hour. Ernsting was rushed to hospital, where he later died.

Worden believes the assailant was trying to rob Ernsting before he died. “Through our investigation and evidence gathered, we believe the stabbing occurred first, which fits the definition of first-degree murder when you commit a robbery,” Worden said.

This is the second robbery he is alleged to have committed that night. Around 7:45 p.m. on Dec. 16, Toronto Police say that a man and two females stabbed and robbed a 65-year-old woman of her purse near Yonge St. and Summerhill Ave. The woman was stabbed four times but survived, and has since been released from hospital.

Nimoh has been charged with robbery, assault with a weapon, and weapons dangerous in relation to that attack.

Tira Thompson, 24, said to be Nimoh’s girlfriend, and a then 17-year-old underage suspect have been charged in the incident with aggravated assault, robbery and possession of stolen property under $5,000. The underage suspect cannot be identified, under the Youth Criminal Justice Act.

Thompson has also been charged as an accessory after the fact to murder, and obstructing a peace officer, in relation to Ernsting’s murder.

Thompson appeared in court Dec. 24. The other woman, now 18, will be appearing in court on Dec. 31.

Worden told Metro News the motive for both attacks is unclear.

“The motivation was they were robbing people for money, and it turned violent, and we’re not sure why,” Worden said.

With files from Jacques Gallant and Metro News