Saint John police say the investigation into the Christmas Day death of 26-month-old Alexzender O'Neil Flint-Kerr may take until late January or early February to complete, largely due to the extra time required to review a head injury death.
Dr. Kenneth Aldape, a neuropathologist with the University of Toronto, said autopsies that involve a brain injury present particular problems and generally slow down the completion of results in most cases.
"The brain is a very soft tissue," said Aldape.
"It might take about a week longer. Most pathologists would like to get the autopsy completed within a month of the death."
Alexzender was rushed to hospital by ambulance from his home two weeks ago, but could not be revived.
Police initially released very few details about what happened other than to say the toddler was reported to have suffered a fall inside the home and the investigation was awaiting autopsy results.
But Tuesday the child's father Oliver Kerr spoke with the Telegraph-Journal about the incident and CBC News has subsequently confirmed several more details.
Police are satisfied evidence at the scene supports the father's claim that Alexzender did strike his head on a bathroom toilet.
But how that happened and whether the injuries suffered are consistent with an accidental fall or other event are issues still being looked into.
Alexzender's parents do not live together and there are no witnesses to the incident since father and son were home alone at the time.
However, Oliver Kerr has co-operated with police and given a full statement.
Police have also spoken with Alexzender's mother, babysitter and neighbours, including one who responded to calls for help.
Reviews expected into child's death
The family held a private funeral service but across social media family members have been sharing their grief, several posting pictures of the young boy.
In one his grandmother, Tamara Flint, holds a mischievous looking Alexzender in a warm embrace.
"So hard letting a lil one go especially when its your own grandson," she wrote.
"My special lil boy."
The death of a child in New Brunswick triggers a number of events, including a near automatic and specialized review by the coroner's office which organizes a child death review committee.
That review, which looks in part at whether institutional failures played any role in a child's death, will likely happen no matter what the police investigation concludes, according to Norm Bossé, the province's child and youth advocate.
"I dare say this is one the child death review committee will look at. I can't speak for them but I'm assuming this is a case they'll want to look at," said Bossé.