TORONTO -- A Toronto man serving a life sentence after admitting to killing his neighbour will get a new trial, an Ontario court has ruled.

The Ontario Court of Appeal ruled last week that Thomas Dupe may have been convicted in the murder of Denna Smith because of hearsay evidence that the Crown failed to prove was trustworthy enough to use in trial.

Five years ago, Dupe was sentenced to life in prison with no chance of parole for 14 years for stabbing 52-year-old Smith multiple times in June 2007, twice piercing her heart, according to the appeal decision.

The case against Dupe was largely based on eyewitness testimony, including that of Smith's friend Myles Groulx, with whom she'd been smoking crack for several days at the time of the murder, the court document said.

The Crown's case rested on the ongoing relationship between Smith and her killer, who lived down the hall from each other in the same downtown rooming house. The Crown submitted that Dupe was "obsessed" with Smith, and was jealous when she slept with other men. It said that was Dupe's motivation in killing Smith.

The Crown said Smith didn't have romantic or sexual feelings for Dupe, and was only interested in being his friend -- and his frequent crack-smoking buddy.

The idea that Dupe was obsessed with Smith came from Groulx, who in a police statement said that while the pair was high on crack, Smith explained that Dupe was "just obsessed with her, like nuts."

But that statement was hearsay, according to the decision. Dupe's alleged obsession with Smith wasn't something Groulx personally witnessed.

Dupe's lawyer for the appeal, Philip Campbell, said his client's case is steeped in "human tragedy, on the margins of society."

He said the appeal decision marks a potential turning point for Canadian law, which he said often allows too much hearsay evidence into the record.

In the appeal decision, Justice David Doherty wrote that Smith didn't have a compelling reason to tell the truth to Groulx. They weren't close friends, hadn't known each other for very long and were high on crack cocaine.

He wrote that if the jury hadn't heard that Dupe was obsessed with Smith, they may not have convicted him of second-degree murder.

A second piece of hearsay evidence Doherty decided should not have been admitted was the police statement of a neighbour named Elsworth Pointer. Pointer told police Dupe was "possessive" of Smith, and that Dupe got jealous if Smith spoke to other men. Pointer died before the trial, so his statement was relayed by a detective.

Doherty said that even if Pointer's police statement was reliable, there was nothing to indicate what Smith told him was truthful.

Not all of Groulx's testimony was hearsay, and in fact he was a star witness, claiming to have seen the slaying happen.

He testified that moments before she was killed, Smith left her room to feed a neighbour's cat. After she left the room, Groulx heard a scream, and found Dupe standing over top of Smith. He said there was a great deal of blood.

"(Dupe) looked at Mr. Groulx, smirked, said nothing and plunged the knife into Ms. Smith's chest," Doherty wrote in his decision.

Dupe testified that he didn't remember stabbing Smith, but didn't contest that he did it. In the initial trial, the defence argued Dupe was drunk and high on the day of the homicide, he had a history of mental disorder and he hadn't been taking his medication.

Crown attorney Roger Pinnock did not return a request for comment before press time, and Campbell said they're still months away from setting a date for the new trial.