The B.C. Crown will ask the Supreme Court of Canada to overturn a ruling that ordered a fourth trial for Kelly Ellard, who was charged with murder in the 1997 death of 14-year-old Reena Virk near Victoria.

Ellard had been convicted of second-degree murder but the verdict was overturned last month by the B.C. Court of Appeal in a 2-1 decision that ordered a new trial.

Crown spokesman Stan Lowe said Wednesday that the importance of the case requires a review by the highest court in the country.

"We've determined that the most appropriate course of action is initiating an appeal to the Supreme Court of Canada,'' Lowe said.

The B.C. criminal justice branch filed a notice of appeal with the court in Ottawa on Wednesday.

"The Branch has determined that the importance of this case requires appellate review by the highest court in the country,'' Lowe said.

It was Ellard's third trial.

Her first trial ended in a guilty verdict that was overturned on appeal. The second trial resulted in a hung jury.

Ellard was charged after the 14-year-old Virk was found beaten and drowned in suburban Victoria.

The case shocked the nation because prior to her murder, Virk was swarmed by a group of teens, most of them girls, and beaten. Six teenage girls were convicted of assault in 1998 for beating that Virk received on the night she died.

The Crown alleges that Ellard and co-accused Warren Glowatski followed her as she tried to go home after the attack and killed her under a bridge on a waterway called the Gorge, near Victoria.

Glowatski, who was 16 at the time of the murder, was convicted of second-degree in the killing and is currently on day parole.

Despite rumours circulating among the high school crowd for more than a week, Virk's body wasn't found by police until Nov. 22, 1997, floating near the bridge.

In the 60-page ruling overturning the latest conviction, two of three judges supported the appeal, saying the trial judge erred in permitting the Crown to elicit further evidence from the witness and failed to properly instruct the jury about it.

"In my view, having regard to the functional approach to reviewing jury instructions, the jury should have been told specifically that (a key Crown witness's) prior consistent statements did not enhance the reliability of her testimony and, further, that those statements could not diminish any concerns the jury might have regarding the effect of external influences on her evidence,'' wrote Justice David Frankel for the majority.

But Justice Richard Low dissented.

"It seems to me that my colleagues are suggesting that the trial judge erred in failing to give a special instruction to the jury with respect to prior consistent evidence that the (key Crown witness) did not give,'' Low wrote in the decision released last month.