One of two men on trial for allegedly plotting to kill scores of people by derailing a passenger train told an investigator he only pretended to go along with the idea in an attempt to deradicalize his co-accused.

A transcript of a four and a half hour interview with an RCMP officer on the day he was arrested shows Raed Jaser repeatedly tried to cast his co-accused, Chiheb Esseghaier, as an extremist with a "disturbed" mind.

"I thought I could help him," Jaser said when asked why he let Esseghaier into his life. "He's sick, he needs help."

A jury is currently deliberating the fate of Jaser and Esseghaier, who face multiple terrorism-related charges.

Jaser pleaded not guilty and his lawyer argued he was only feigning interest in alleged terror plots as part of an elaborate con to extract money from his co-accused and an undercover FBI agent who befriended them.

Esseghaier chose not to participate in his trial because he wanted to be judged by the rules of the Qur'an. A not guilty plea was entered for him by the judge presiding over the case.

On the day of his April 2013 arrest, Jaser told the RCMP officer interrogating him that he had been trying to persuade Esseghaier to "change his mindset."

As the officer revealed he knew Jaser and Esseghaier scouted a railway bridge as a potential target for their alleged attack, Jaser claimed he hadn't been encouraging Esseghaier.

"I don't wanna do nothing of what this is," he said. "It's like deradicalizing somebody. It takes a long time, it's a process. Okay. It's not that simple right ...you have to walk with them."

'It's role play man'

Jaser added that he tried to "get into" Esseghaier's head but his efforts didn't work.

But what good could come from scouting a railway bridge as a potential target for an attack, the officer asked.

"One on one talk. I don't know. Maybe heart to heart," Jaser offered as an explanation. "I don't know what exactly was going through my head."

At one point, the RCMP officer played an excerpt from a secretly recorded conversation the men had on the railway bridge during which Jaser is heard saying "that's the target" while a Via Rail train goes by.

"I'm just trying to get into your mind as to why you would say that's the target," the officer asked.

"It's just ... uh ... it's role play man," Jaser said.

Jaser also repeatedly told the officer that he was the "wrong person" to arrest and that police needed to look at the "bigger picture."

"Who in their right mind would do something like this," he said of the alleged plot.

"Well you guys were planning it," the officer replied.

"Not planning, no," Jaser said.

When asked why he didn't call police if he suspected a terrorist plot in the making, Jaser said he had tried to find a solution himself.

"If you see someone doing something wrong ... you wanna try to reach out to him. You don't wanna come out and shove it in their face," he said.

Jaser also told the investigator he had tried to deradicalize another man in the past, although he couldn't remember that individual's name.

The court released the transcript on Thursday.