The parents of a Calgary teenager are facing first-degree murder charges after tests concluded their son died from complications due to untreated diabetes.

Alex Radita's parents, Rodica and Emil Radita, were arrested Tuesday morning.

The death of their son in May 2013 was labelled suspicious after the emaciated 15-year-old was found in medical distress at his home in northwest Calgary.

Police say tests revealed the boy, who had Type 1 diabetes, died from a bacterial infection that arose from complications related to neglect and starvation. 

The boy had once been in the care of social services in British Columbia.

In 2003, while the family was living in Surrey, B.C., child services took Radita away from his family after he was admitted to intensive care at B.C. Children's Hospital for being extremely malnourished and losing his hair.

During that time, B.C.'s Ministry of Children and Family Development applied to have the boy permanently removed from his parents' care.

B.C. judge returned boy to parents

However, B.C. Supreme Court Justice J.G. Cohen found the ministry application was made "without any reasonable effort to maintain this large and otherwise well-parented family."

Alex Radita

Alex Radita died in May 2013 after being found in medical distress at his home in northwest Calgary. (Facebook)

According to court documents, the judge said the social worker didn't allow the parents to help,  even though they could have. 

That showed a "monumentally inappropriate lack of trust between the social worker and parents," according to Cohen, who said a new social worker should have been found at that point.

The judge said the boy's parents were not blameless, but he believed the boy would be safe at home.

The boy was returned to his family in 2005. 

After six months of supervision, the family was left alone and eventually moved to Alberta, where the boy died last May, almost ten years later.

The teen's health declined and he was confined to his room, bedridden and wearing diapers when he was found, according to police.

He was home-schooled so outsiders did not see his deterioration, police said. 

"Although the motive for not providing treatment is unknown, police do not believe it was based on religious beliefs," said a statement from police. 

The case has raised questions about how Alberta and B.C. share social services information.

With files from CBC Calgary