CALGARY -- A defence lawyer says the parents of a diabetic boy who died of starvation and lack of treatment are guilty of manslaughter for their "well-meaning but ineffective care."

Emil Radita, 59, and his wife, Rodica, 54, have pleaded not guilty to first-degree murder in 15-year-old Alexandru's death.

The Raditas didn't intend to kill their son, Andrea Serink said Friday in her rebuttal to the Crown's case.

"The culpability lies in that his care did not meet the appropriate legal standard. We're saying where they're culpable is that they didn't provide him with the level of care that he needed," said Serink, who represents Rodica Radita.

"The Raditas are guilty of manslaughter, not murder."

Alexandru weighed just 37 pounds when he died in 2013.

"You have to have something more to say than you are beyond a reasonable doubt convinced that they really appreciated the significance of how dire his medical condition was," Serink told the judge hearing the case.

"I agree with you that these facts need to be viewed dispassionately but -- manslaughter or murder -- it's the death of a young boy, so the passion of the court is engaged at each level," said Justice Karen Horner.

Serink said there was insulin in the home, even though some of it may have expired, and there's no evidence the couple denied their son medical care.

She said the Crown has failed to prove that the Raditas planned Alexandru's death.

"There was no diary seized from the accused's home that explained their state of mind, or the plan, or other things that would assist in terms of the Crown theory. There's just a complete absence of evidence."

Crown prosecutor Susan Pepper said that any reasonable person would have known lack of treatment would have fatal consequences for Alexandru.

"Really the question is was there an intention to withhold care ... leading to certain consequences that they would expect to have occur? That's the intention," Pepper said in her final remarks Friday.

"The motive as to why they did it ... that is a separate issue."

Witnesses testified the Raditas refused to accept that their son, one of eight children, had diabetes and failed to treat his disease until he was hospitalized near death in 2003. One witness described the teen as nothing more than "skin and bones."

Social workers apprehended Alexandru after his October 2003 hospital admission and placed him in foster care -- where he thrived -- for nearly a year before he was returned to his family.

Testimony also indicated that after the family moved to Alberta, he was enrolled in an online school program for one year but never finished. The boy never saw a doctor, although he did have an Alberta health insurance number.

The trial heard that the parents' religious beliefs included not going to doctors. The day the Alexandru died the family went to church and said that the boy had died, but that God had "resurrected him."

Horner has reserved her decision. A date is to be set Oct. 28 for when she will deliver a verdict.