Two teenagers accused of plotting to murder classmates at a St-Hyacinthe high school are back in a psychiatric hospital.

The 14 and 16-year-old boys made a brief appearance in St-Hyacinthe court Tuesday morning after spending 30 days undergoing psychiatric assessment.

After hearing from their doctors, the judge ordered the two to return to psychiatric custody because he wanted to know more information.

Defence lawyer Andre Blanchette said he understood the request.

"The court asked for more precision. We want to know exactly what the psychiatrist will deliver in the conclusions of his report," said Blanchette.

“I told my client it was in his best interest to go for a new assessment,” added defence lawyer Francis Savaria.

The boys, who looked thin, frail, and younger than their years, will remain at the Pinel Institute until their next hearing on Nov. 15, 2016.

Parents from both families were in court, and they did not say a word to each other, nor to reporters observing the proceedings. They remained calm and quiet during the brief hearing.

The boys were already facing 18 charges including conspiracy to commit murder, sexually assaulting at least one girl and administering a date rape drug.

Five new charges were laid against both boys, including  making threats toward classmates and administering a noxious substance to a female victim.

Both have pleaded not guilty.

The alleged plot was uncovered earlier this year by the mother of one of the boys after she allegedly found threatening messages on her son's Facebook account.

Both boys attended Ecole Polyvalente Hyacinthe-Delorme in St-Hyacinthe. Police found a knife and a number of sleeping pills inside their lockers

Because of the Youth Criminal Justice Act neither the accused nor the alleged victims can be named.