Ontario's top court has formally acquitted a woman who pleaded guilty 25 years ago to killing her three-year-old

The decision in favour of Maria Shepherd, of Brampton, Ont., came after a short hearing at the urging of both Crown and defence. 

The Court of Appeal for Ontario took just a few minutes to render its decision.

Shepherd pleaded guilty in 1992 to manslaughter in the death of Kasandra Shepherd following evidence presented by  now-disgraced pathologist Charles Smith.

Defence lawyer, James Lockyer, with the Association in Defence of the Wrongly Convicted, told the justices that other experts have now concluded Smith's opinion was seriously flawed.

'Miscarriage of justice'

Crown attorney Howard Leibovich agreed, and urged Shepherd's conviction be quashed in favour of an acquittal.

He said a "miscarriage of justice" had occurred, and Shepherd would not have pleaded guilty had she known what she knows now.

"This is a tragic case," Leibovich said. "Kasandra deserved better. Her family deserved better. [Shepherd] deserved better."

Speaking for the court, Justice David Watt exonerated Shepherd, saying Smith's evidence had been the "linchpin" for the Crown's case against her.

The justice system, he said, held out a "powerful inducement" for her to plead guilty given that she faced a possible lengthy prison sentence had she been convicted after a trial, Watt said.

"The appeal is allowed," Watt said. "The plea of guilty and conviction is set aside and an acquittal entered."

Smith's autopsy on the girl was one of many suspicious child deaths he had done, several leading to wrongful convictions.

Speaking to reporters outside the court shortly after her conviction was quashed, Shepherd said she was "elated" by  the decision after wearing the label of "baby killer" for more than two decades.

"This didn't come without a lot of quiet tears and anguish at home," she said. "I am innocent. I didn't do anything but care for Kasandra. I loved her as if she was born to me."

Shepherd said she forgives Smith, who she said was treated "like a God" by those in the court system.

A 'long and terrible ordeal'

A review of Smith's work and subsequent public inquiry uncovered numerous examples where he made serious mistakes. He was stripped of his medical licence in 2011.

Court documents show Kasandra began vomiting and became unresponsive in April 1991 after a long period of ill health. She died two days after being admitted to hospital.

Smith concluded she died from trauma due to at least one blow of "significant force."

Shepherd had told police she pushed the child once, with her wrist and watch hitting the girl on the back of the head, but said she didn't believe the blow could have killed the girl.

'I did not cause Kasandra's death'

Her lawyer at the time consulted an outside expert who agreed Smith's theory was reasonable, prompting her to plead guilty to manslaughter. She was sentenced to two years less a day.

"I did not cause Kasandra's death, and my conviction for doing so has haunted me ever since," Shepherd said in a recent affidavit.

Forensic experts have now concluded Smith's testimony at Shepherd's court hearing contained a "number of significant

The theory now is that Kasandra may have had a previous brain injury that caused seizures or that she suddenly developed a seizure disorder that killed her.