FREDERICTON -- A New Brunswick man accused of murdering four people in a shooting spree in Fredericton last year has been ordered to undergo another psychiatric assessment to determine if he is fit to stand trial.

Matthew Raymond is charged with the first-degree murders of Fredericton police constables Sara Burns and Robb Costello and civilians Donnie Robichaud and Bobbie Lee Wright.

Raymond has already undergone an assessment that found him fit to stand trial, but on Friday Court of Queen's Bench Justice Fred Ferguson said he's ordering another assessment "as a result of hearing utterances and reading materials that have been filed with this court over time."

Ferguson told the court that fitness to stand trial "is an ongoing obligation of the court to determine, and from the beginning of proceedings to the end of the proceedings, every accused person must be fit to stand trial."

Fitness means that an accused understands the charges against him and can instruct a lawyer on how he wishes to be defended.

The exact reasons that prompted the assessment order and other details of the pre-trial hearings remain under a publication ban.

The psychiatrist, Dr. Scott Woodside of Toronto, is to file his report by the end of next week, but it will be up to a jury -- once it is chosen -- to determine if Raymond is fit to stand trial.

"Because Mr. Raymond is charged with first-degree murder and because it will be a trial by jury, the jury has to decide whether he is fit or unfit," defence lawyer Nathan Gorham said outside the court.

Jury selection is scheduled to begin on Sept. 30.

Gorham said if the jury were to find Raymond fit, then the trial would proceed.

"Hypothetically if a jury found someone unfit, what would happen is they would receive treatment so that they would then be able to stand trial. It's a mechanism to ensure a fair trial," he said.

Raymond is alleged to have fired from his apartment window with a long gun, killing the two civilians as they loaded a car for a trip and the two police officers as they responded to the scene.

Costello, 45 was a 20-year police veteran with four children, while Burns, 43, had been an officer for two years and was married with three children.

Robichaud, 42, had three children and had recently entered into a relationship with 32-year-old Wright when they were killed.

Earlier this month, on the first anniversary of the killings, thousands of people joined hands in Fredericton in a show of support for the families of the victims and the community.