TORONTO - Two men charged in the fatal shooting of 15-year-old Jordan Manners in a Toronto high school are expected to face a second trial, Attorney General Chris Bentley said Monday.

Their first-degree murder trial ended in a mistrial Friday, when the jury told the judge it could not reach a unanimous verdict after four days of deliberations.

"This matter is going to be back before the court on April 1," Bentley said.

"I understand it's the Crown's intention to have a second trial."

The co-accused cannot be named because they were under 18 at the time of the attack in May 2007.

Bentley wouldn't comment on an unusual move by Justice Ian Nordheimer, who told the court -- but not the jury -- that two teenage witnesses "undermined the process" during the trial.

Nordheimer called on the attorney general to investigate but Bentley said he would not comment while the case was before the court.

"I'm going to let that process unfold as it should," Bentley said.

"The submissions about what should or shouldn't happen, what did or didn't happen, can be made in court before the judge."

However, opposition New Democrats said judges "just don't say things off the cuff," and insisted Bentley had a responsibility to immediately investigate the judge's concerns.

"When a very experienced judge like Justice Nordheimer raises the concerns that he did, that cries out for a thorough investigation," said NDP justice critic Peter Kormos.

"The public is shocked when this happens and it's incumbent upon the attorney general to address those concerns and to do it promptly and thoroughly, or else the attorney general is once again contributing to a general mistrust in our criminal justice system."

Manners, who was in Grade 9, was the first person shot dead inside a Toronto high school.

He was found in the stairwell of C.W. Jefferys Collegiate in the city's north end.

His death sparked alarm about school safety. Police officers were posted to high schools, reviews were commissioned to examine the issue, and legislation was passed aimed at protecting students.

The jury had indicated to the judge Thursday they were at an impasse.

Nordheimer told them to return to their hotel to get a good night's sleep, and then to do their "utmost" to come to a verdict.

On Friday, however, they said they were hopelessly deadlocked and the judge declared a mistrial.

During the trial two key witnesses, teenaged girls, backed away from statements they had given to police.

The Crown argued the accused pulled Manners down the stairs in a planned killing.

The prosecutor alleged one man shot Manners and the other rifled through the pockets of the dying teen.