A man convicted and then acquitted of killing two people in a shooting that sparked terror and chaos in Toronto's landmark Eaton Centre almost six years ago will have to face a new trial after Canada's top court refused on Thursday to get involved in the case.

The Supreme Court of Canada decision leaves intact last year's ruling from Ontario's top court in favour of Christopher Husbands, who had earlier been convicted of second-degree murder and other offences related to the shooting.

In a unanimous decision last July, Ontario's top court overturned Husbands' convictions based on defence arguments about how jurors had been selected. The Appeal Court, finding that the trial judge had improperly rejected a defence request related to jury selection, ordered a new trial. The prosecution appealed to the Supreme Court, which said Thursday it would not weigh in.

The killings of Nixon Nirmalendran, 22, and Ahmed Hassan, 24, and the wounding of five others at the popular downtown mall in June 2012 sent hundreds of patrons scrambling for their lives. A pregnant woman was trampled in the mayhem and a 13-year-old boy was shot in the head, but survived.

Husbands, charged with first-degree murder, admitted responsibility for the havoc in the crowded food court but denied going to the mall intending to kill anyone. He maintained he was suffering from post-traumatic stress disorder when he encountered a group of men he believed was out to get him and opened fire on them in a panic.

The jury, with then-Ontario Superior Court justice Eugene Ewaschuk presiding, convicted him of second-degree murder and aggravated assault. Ewaschuk sentenced Husbands to life in prison with no chance of parole for 30 years.

But it was a ruling by Ewaschuk at the outset of the hearing related to jury selection that prompted the Ontario Court of Appeal to quash the convictions and order a new trial.

The issue related to whether the first two jurors of a panel hearing a case -- called triers -- accept the selection of the remaining jurors, a situation known as static triers. Alternatively, each newly selected juror replaces one of the first two triers in selecting the next member of the panel, a situation known as rotating triers.

Parliament amended the Criminal Code in 2008 to allow for static triers -- meaning the same two people pick the entire jury -- but only if the defence makes the request. In the Husbands' case, Ewaschuk imposed static triers over objections from the defence.

As a result, the three-member appeal panel said the jury was improperly constituted and the verdict could not stand.

"Expressly and repeatedly, counsel wanted rotating triers," Justice David Watt wrote for the Appeal Court. "Yet the trial judge forged ahead, despite the entreaties of defence counsel, without any inquiries of the trial Crown about her position, and seemingly oblivious to the confining language of the enabling legislation."

The Crown did not contest the jury's second-degree murder finding -- despite the original first-degree murder charge in the case -- meaning that's the main charge Husbands would face at a new trial.