VANCOUVER -- A British Columbia man convicted of killing three women and a teenage girl deserves a new trial because a judge failed to disclose concerns about his defence counsel's "unethical behaviour" until after he had been sentenced, a lawyer argued Wednesday.

Cody Legebokoff was sentenced to life in prison with no chance of parole for 25 years by a judge in Prince George, B.C., for the first-degree murders of 15-year-old Loren Leslie, 23-year-old Natasha Montgomery and Jill Stuchenko and Cynthia Maas, who were both 35.

His lawyer Eric Gottardi told the B.C. Court of Appeal on Wednesday that even though the case against Legebokoff was "horrific," and the evidence "overwhelming," the appearance of unfairness at the trial means it must be heard again.

"This appeal is about the system and the public confidence in the system," said Gottardi, who wasn't Legebokoff's trial lawyer. "This was a slam-dunk Crown case. The judge should have bent over backwards to ensure the accused had a fair trial, and he didn't. This verdict cannot be allowed to stand on that basis."

His argument hinged on the judge's rejection of a defence application in 2012 to have the trial heard in Vancouver. The written reasons for the ruling were only released after Legebokoff was convicted and sentenced in 2014.

Justice Glen Parrett said in those reasons that Legebokoff's counsel had exaggerated and distorted evidence in the application to have the trial moved. He described the defence lawyer's arguments as "misleading" and a "recasting of reality," said Gottardi.

He argued that the judge should have informed Legebokoff before the trial that he thought his lawyer's behaviour was unethical, so that Legebokoff could have considered retaining a new lawyer or filing a bias application to have Parrett removed.

During Wednesday's hearing, the Crown and Gottardi agreed that Parrett's characterization of Legebokoff's defence counsel was wrong and that the lawyer hadn't misled the court.

Gottardi said he was not arguing that the judge was prejudiced toward his client. Rather, he said Parrett's actions created a perception of bias and interfered with Legebokoff's right to choice of counsel, which led to a miscarriage of justice.

All three appeal judges on the panel grilled Gottardi on his argument, questioning whether trial judges should be required to reveal every concern they have about the behaviour of lawyers.

"It seems to me for your argument to hold together, there must be an affirmative duty on a trial judge to express those concerns any time they arise," said Justice David Frankel.

Gottardi's co-counsel, Mila Shah, replied that they were not arguing that every failure to disclose a concern should be grounds for appeal, only when it escalates to a miscarriage of justice.

Crown lawyer David Layton said trial judges must retain the discretion to decide whether to disclose concerns and when.

"They are best placed to ascertain the dynamics of the trial, see the personalities of the actors, to gauge how people might respond to any intervention they might think fit."

The appeal court judges reserved their decision.

Legebokoff's trial heard that his clothing contained the DNA of Montgomery and Maas, while DNA matching Stuchenko was found in Legebokoff's apartment. Identification belonging to Loren Leslie and a blood-stained pipe wrench and knife were also found in the man's truck, the jury heard.

Outside court, Doug Leslie, father of Loren Leslie, said there was "no miscarriage of justice whatsoever."

"(Legebokoff has) made his bed. He's got to sleep in it."