TORONTO - A public inquiry heard today that problems involving the work of discredited pathologist Dr. Charles Smith could go back as far as 1981.

A review of child deaths he handled turned up an additional 13 cases that occurred between 1986 and 1991, although it remains unclear how many of those resulted in convictions.

The Goudge inquiry was prompted by a review of 45 cases Smith handled between 1991 and 2001 which led to criminal proceedings in 20.

Ontario's chief forensic pathologist, Dr. Michael Pollanen, said the earlier cases were brought to his attention during the review - and those are now being looked at as well.

In a memo written earlier this year, Pollanen wrote that "some adverse inferences" could be drawn against Smith in "many" of the earlier cases.

On Monday, Smith's lawyer read a letter to the inquiry in which the doctor admitted making mistakes and apologized for them.