One of the men convicted of plotting to derail a Via Rail passenger train between New York and Toronto is now being treated for schizophrenia and wants to appeal his life sentence, a court heard on Wednesday.

Chiheb Esseghaier and his accomplice Raed Jaser were found guilty in 2015 of conspiring to commit murder for the benefit of, at the direction of or in association with a terrorist group, as well as several other charges.

Esseghaier, who up until recently did not believe he was mentally ill and refused treatment, chose to represent himself at the trial, during which he ranted, fell asleep and spat in court.

While both men have already launched an appeal of their conviction, Esseghaier is now being treated with anti-psychotic drugs and realizes the "significance" of his sentence, his court-appointed lawyer said Wednesday.

Erin Dann said Esseghaier was suffering from schizophrenic delusions that caused him to believe he was going to die and ascend to heaven on December 25, 2014.

Although Chiheb Esseghaier is representing himself, lawyer Erin Dann is assisting him as a court-appointed amicus. (CBC)

"He understands that to be a delusion. He understands it is currently 2017 and that his previous delusions in that regard were products of his mental illness," Dann said.

Esseghaier has instructed Dann to ask the Ontario Court of Appeal for more time to appeal his sentence.

"The diagnosis of schizophrenia has now been confirmed by a number of doctors. He has been treated with anti-psychotic medication and he is certainly doing much better than when I spoke to him soon after the verdict," Dann said in an interview following a brief hearing on Wednesday.

'Errors' made at trial

While Esseghaier was never examined prior to or during his trial, he underwent two psychiatric assessments ahead of sentencing.

Justice Michael Code ultimately ruled that Esseghaier was fit to be sentenced and there was not "a scintilla of evidence" from the pretrial and trial to suggest he was unfit to stand trial.

But Dann will argue to the Court of Appeal that Esseghaier's mental state meant he was not "meaningfully present" during his trial and unable to "fully engage" with the justice system.

"I think there were errors made at the trial in that regard," she said.

Chiheb Esseghaier had to be removed from the court at one point during his sentencing hearing.

Esseghaier was initially imprisoned at a correction centre in Quebec, but Dann revealed on Wednesday that he has since been moved to a facility in Abbotsford, B.C.

Dann said she does not know why this move was made or what led to Esseghaier's acceptance of his mental illness and treatment for it, something he had previously refused.

"I think it will be important to look at the progress he has made since coming under treatment for schizophrenia and the results of the treatment with anti-psychotics. That may also give us some insight into what bearing those mental health issues were having on him during the trial," Dann said.

Jaser appeal

Jaser's lawyer, John Norris, said questions about Esseghaier's are a big concern for his client.

Jaser sought to be tried separately from Esseghaier but the request was denied.

"It has a direct bearing on the severance question. For example, was Mr. Jaser required to have a joint trial with somebody who was in fact unfit to stand trial? That's a deeply troubling question that we'll be arguing fully," Norris said in an interview.