The Ontario Court of Appeal on Monday began hearing the case of a Sault Ste. Marie man who was convicted of murder based, in part, on the now-questionable testimony of pathologist Dr. Charles Smith.

William Mullins-Johnson is bringing his case to the Ontario Court of Appeal on Monday.
(Canadian Press)

William Mullins-Johnson was convicted in 1994 of killing his four-year-old niece the year before, despite an absence of forensic evidence linking him to the crime.

He spent more than 12 years in prison before being released in 2005 when evidence surfaced that Smith had lost the tissue samples that could have shown the child died of natural causes.

The Court of Appeal will consider whether to acquit Mullins-Johnson, or even declare him innocent.

Smith, once considered a leading forensic child pathologist, came under further fire in April 2007, when a coroner's review concluded that 20 of the child autopsies he performed were questionable.

Mullins-Johnson's case was among 13 of the 20 that resulted in criminal convictions.

The Ontario government has ordered a full public inquiry into Smith's work.

In July, Canadian Justice Minister Rob Nicholson referred Mullins-Johnson's case to the Ontario Court of Appeal.

A Department of Justice media release issued a statement at the time that said Nicholson was satisfied "there is a reasonable basis to conclude that a miscarriage of justice likely occurred" in Mullins-Johnson's conviction in 1994.

Ontario Attorney General Michael Bryant has said the conviction "cannot stand" and that the Court of Appeal should acquit Mullins-Johnson.