LETHBRIDGE, Alta. - The medical examiner who did an autopsy on a 19-month-old boy says there was no suggestion a lack of oxygen had anything to do with the child's death.

David and Collet Stephan are on trial in Lethbridge, Alta., on a charge of failing to provide the necessaries of life for their son Ezekiel. They treated the toddler with alternative and natural medicines instead of seeking medical assistance right away.

Dr. Bamidele Adeagbo on Tuesday repeated the view he also presented in court a day earlier that Ezekiel clearly died of bacterial meningitis and a lung infection in March 2012.

David Stephan, who's representing himself, pointed out that the first ambulance that tended to his son was missing key equipment, so his son was without oxygen for almost nine minutes.

“Is it fair that you did not take into consideration the amount of time Ezekiel had not had air in that ambulance in your findings?” Stephan asked.

“There is no evidence that Ezekiel did not have air,” Adeagbo replied.

The pathologist, who was working as a medical examiner in Calgary in 2012, testified by video from Indiana, where he now works as a pathologist.

He said it's important to keep an open mind during an autopsy and to take tissue for study, including from the brain. Adeagbo said there were no signs of any effects from oxygen deprivation.

“The issue of the lack of oxygen ... was answered totally by the pathology,” he said.

“If there was oxygen deprivation injuries, I would have seen it. It was not in the brain.”

Stephan also asked Adeagbo whether his work as a medical examiner was influenced by others. On Monday, Stephan produced a letter from Alberta Justice to the medical examiner's office warning about Stephan's background.

“There is information to suggest the family and extended family are sovereign citizens, also known as being from a sovereign or freedom group. Those from this group tend to be anti-government and anti-establishment and there are suspicions that they are typically well-armed,” Stephan read from the document.

Adeagbo replied that the office is independent and his only concern was finding out why Ezekiel had died. He said the warning didn't influence the way he did the autopsy.

“At this point, whether it's the Taliban or whatever it is, I don't care,” said Adeagbo.

“Do you feel it's appropriate on the day of the autopsy that you were given a letter with prejudicial information? Did this letter at all affect your opinion moving into the autopsy of Ezekiel Stephan?” Stephan asked.

“No, it did not.”

Stephan, as well as the lawyer representing his wife, are challenging the pathologist's qualifications to testify as an expert witness. Stephan had already questioned the doctor for seven hours by midday Tuesday. Until he is accepted as a witness, none of Adeagbo's comments are considered to be evidence.

It is the second trial for the Stephans. A jury found them guilty in 2016, but the Supreme Court overturned the convictions last year and ordered a new trial. This one is before a judge alone.