Affable. Arrogant. Decent. Slovenly. Inquiry witnesses have painted a curious portrait of Dr. Charles Smith. He gets to tell his side tomorrow.

Over the last two months, 41 witnesses have painted a curious, somewhat incongruous picture of the man at the centre of the Inquiry into Pediatric Forensic Pathology in Ontario.

Dr. Charles Smith has been described by some as decent, affable and warm. Deeply religious, the evangelical Christian would often talk to his co-workers about his faith. He deplored swearing and wouldn't permit it in his office. Highly respected, he was considered for almost two decades Canada's foremost pediatric forensic pathologist, an icon in his field.

Others have portrayed Smith in a far less flattering light. He was slovenly, disorganized and tardy. While cleaning his chronically messy office, a secretary once discovered a dish containing human remains. He showed questionable judgment, once taking his young son to a graveyard for the exhumation of a child's body. He could be haughty – the inquiry hearing how he challenged a police officer who dared give him a speeding ticker if she knew who he was. He fabricated stories to cover his tracks.

But for years, Smith's many foibles were forgiven or ignored because he was, after all, Canada's guru of pediatric forensic pathology.

Smith, 57, is scheduled to make a highly anticipated appearance at the inquiry tomorrow, when he'll undoubtedly be grilled about how he fell from his lofty perch, how he wasn't nearly as competent as his many admirers assumed and, most importantly, how he came to err in 20 child death investigations between 1992 and 2002.

His mistakes contributed to parents and caregivers being convicted, charged or otherwise implicated in the deaths of children. They spent months, even years behind bars and some had surviving children removed from their custody, temporarily or permanently. Families spent life savings trying to defend themselves.

To date, few individuals affected by Smith's decisions have attended the public hearings. But that's expected to change this week. Lawyers for some have indicated their clients want a first-hand look at the man who turned their lives upside down.

"After so many years, they just want to hear his explanation, if he has one, and they want to hear if he's actually going to really apologize for what went wrong," says Peter Wardle, a lawyer representing some of these individuals. An apology issued through Smith's lawyer at the beginning of the inquiry was "very vague," he says.

While the inquiry is looking at systemic shortcomings in the world of pediatric forensic pathology, there is much fascination with Smith. A book is in the works and a movie is being planned. Thorny questions abound. Who was watching him? How could it be that the man in charge of suspicious child death investigation in Ontario was not up to snuff? Why were his mistakes allowed to continue for so long? What made Smith tick?

"I think everybody involved in the inquiry is interested in what he's like and how he gives his evidence," Wardle says. "Of course we're all curious."

Past interviews with the Toronto Star reveal that Smith had a strong passion for his work, which was fed by strong religious convictions. He worshipped with the Summit Community Church, an evangelical congregation in Richmond Hill, and he said in 2005 that his faith imbued him with the belief that he had a purpose in life – to provide answers to parents who lose babies.

The interviews also showed he had strong feelings about child abuse. "I've got a thing against people who hurt children," he said.

Smith was born on May 22, 1950 at Grace Hospital on Church St. He was given up at three months and spent years trying to find his biological mother. He finally tracked her down on her 65th birthday, only to have her hang up on him.

His adoptive father was with the Canadian Armed Forces and, as a youngster, he moved all over Canada and Germany. After high school in Ottawa, he moved to Saskatoon to attend university.

His 25-page curriculum vitae, submitted as evidence at the inquiry, is impressive.

He graduated from medical school at the University of Saskatchewan in 1975. He came back to Ontario in 1980 and started doing autopsies for the provincial coroner in 1981. He was an associate professor at the University of Toronto. He authored numerous papers on pediatric pathology, with titles such as Axonal injury and the neuropathology of shaken baby syndrome. And on a number of occasions, he travelled with Ontario's former chief coroner Dr. Jim Young to conferences the United States where, together, they presented papers with titles such as Death from child abuse versus falls.

In 1992, Smith was appointed director of the Pediatric Forensic Pathology Unit of Ontario – the apex of his career. His bosses at the Office of the Chief Coroner of Ontario had the highest of praise for him, referring to him as a guru and icon. Others, it came out during the inquiry, were loathe to critique his work because he was top dog.

Ironically, while Smith did a residency in pathology, he didn't have any real training qualifications as a forensic pathologist. This isn't surprising because, unlike the United States or Britain, Canada has no training standards in forensic pathology. But others in the field went to the U.S. for accreditation. And only now is the Royal College of Physicians and Surgeons of Canada taking steps to make forensic pathology a subspecialty. Still, despite his lack of official training, Smith was accepted in many court cases as an "expert witness" in pediatric forensic pathology.

His resumé offers some personal insights. It states he's a member of the board of elders of his church; that he's a member of the Ontario Cattlemen's Association; and that he's married to another doctor and together they have two children.

But much has changed for him, both personally and professionally, since it was prepared in 2001.

His marriage fell apart because of the stress. He no longer lives north of the city on a farm, where he used to raise cattle.

He resigned in disgrace from the Hospital for Sick Children in 2005 and moved west where he took a job as a pathologist at Saskatoon City Hospital. But his past caught up with him and he was dismissed after only four months. He then headed further west and now resides in Victoria.

But even there he couldn't escape his past. Now he's an expert witness in a hot seat of his own making.

Some individuals whose lives were affected by Charles Smith's errors are expected to attend the public inquiry this week. They include the following people, some of whom can be referred to only by their initials or first name because of a publication ban:

• Maurice Gagnon and daughter Lianne, of Sudbury. Lianne came under suspicion for the 1995 death of her son, Nicholas, 11 months, after Smith had determined the boy had suffered "non-accidental" blunt force trauma. While there was never enough evidence to charge Lianne with homicide, child welfare authorities seized custody of her second child. Her father, Maurice, led a fierce and successful battle to get the child back and clear his daughter's name and, in doing so, used up the family's life savings. Lianne had always maintained Nicholas went into distress after hitting his head. An expert pathologist who reviewed the case disagreed with Smith and said the cause of death was undetermined.

• DM and his wife, from Timmins. DM is another father who waged a tough fight on behalf of his daughter. SM, who won't be at the inquiry, was charged with manslaughter in 1988 when she was just 12. She had been babysitting a 16-month-old girl who fell down the stairs and suffered fatal brain injuries. Smith argued that explanation wasn't plausible and said the toddler died of shaken baby syndrome. The family went bankrupt defending her against the charge. A slew of experts refuted Smith and SM was acquitted.

• Maureen, of Toronto. She had been caring for 3-year-old Tyrell one evening in 1998 when he hit his head while playing, suffering a fatal injury. Maureen was charged with second-degree murder after Smith said that children don't die from such accidental falls. Other pathologists disputed this and the charge was eventually dropped. Meantime, she had temporarily lost custody of her two children.

• Brenda Waudby and daughter, Justine, of Peterborough. Brenda's other daughter, Jenna, 21 months, died of blunt trauma to the abdomen in 1997. Brenda was charged with the second-degree murder because of an error Smith made in the timing of the death. Justine was removed from Brenda's custody for almost two years while the case was before the courts. The charge against Brenda was dropped and a 14-year-old male babysitter was subsequently convicted of manslaughter.

• William Mullins-Johnson, of Toronto. He was wrongly convicted in 1994 for killing and sodomizing his 4-year-old niece, Valin, based on evidence from Smith. The conviction was overturned last year because of Smith's discredited testimony. Mullins-Johnson had spent 12 years behind bars.