A 57-year-old Toronto man will appear in court Tuesday on a charge of second-degree murder after a woman he allegedly stabbed in the neck at a Chinatown restaurant died of her injuries over the weekend.

Chi Kuan is accused of stabbing Guang Lu, 45, after an altercation Wednesday afternoon in the kitchen of the Dundas Street West restaurant where they both worked.

Arrested at the scene, Mr. Kuan had originally been charged with attempted murder and aggravated assault but the charge was upgraded after Ms. Lu died in hospital Saturday.

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She was without vital signs when emergency responders rushed her to a Toronto trauma centre, but it had been hoped that after surgery she was going to survive. Her death raises the city's homicide total for 2011 to 46.

In another stabbing homicide investigation, detectives held an emotional news conference Monday in an appeal for tips into the death of Michael Pimentel, a 24-year-old father and construction worker fatally stabbed in the early hours of New Year's Day as he left a party in downtown Liberty Village,

Relatives of Mr. Pimentel and his girlfriend wept and consoled each other as they joined police in urging anyone with information to step forward. At least 100 people are thought to have been in the vicinity at the time.

"Help us find that person out there," his sister, Carla, said of the killer. "He can hurt somebody else out there. Please, let's get him off the streets."

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"If anyone has any information ... please come forward," his brother Josh said. "Whoever did this is a coward."

The father of a five-year-old girl, Mr. Pimentel suffered multiple stab wounds when he got into an altercation with at least one person at around 3 a.m. near East Liberty Street and Hanna Avenue, police said.

He died several hours later in hospital.

He was the second homicide victim of the year. Two hours after he was stabbed, 20-year-old Jamahl Franklin was shot dead in a school yard on Hupfield Trail, near Finch Avenue East and Neilson Road, in Scarborough. He was pronounced dead at the scene.

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Also on Monday, Peel Regional Police announced a second arrest in the stabbing death of 19-year-old Kevin Pham, who died in hospital last Wednesday.

Elon Washington Brooks, 19, turned himself in Sunday and now faces a charge of second-degree murder.

A 17-year-old who cannot be identified has also been charged with murder in the Pham investigation.