Jamie Arthur Banks became involved in the bizarre extortion plot under the misapprehension he may have been the target of the supposed hit, his barrister told the ACT Supreme Court on Tuesday.

Banks, 29, was appearing there for a sentence hearing, having pleaded guilty in May to charges of making a demand with a threat to kill and possessing a prohibited weapon.

The father of three entered the pleas less than a week before he was scheduled to stand trial.

Court documents show Banks and co-offender Jesse Christopher Kirkwood, 31, attended a Chapman home last August while looking for a person known as "Jimbob".

"Jimbob" was known to visit a friend at this property but he was not there that day, and the offenders instead found his friend's housemate.

Banks and Kirkwood forced this man into his car, according to chief Crown prosecutor Anthony Williamson's written submissions, and demanded that he drive them to wherever he thought "Jimbob" might be.

"Kirkwood told the victim that there was a 'hit' on ['Jimbob'] and they intended to kill him for $25,000, unless they received that sum through some other means before they located ['Jimbob']," Mr Williamson wrote.

"The victim was threatened with a samurai sword."

During the subsequent drive, Kirkwood claimed to be a "professional kidnapper" and said he would "kill someone for a certain amount of money".

Banks, who was abusing methamphetamine at the time, added that he "would like to grab a gun and kill someone".

Later in the car trip, Kirkwood tried to show the victim a video that apparently showed what had happened to someone who had tried to "do a runner" during a past kidnapping.

When they arrived at a Kambah address, where the victim had believed they might find "Jimbob", the man was not there.

The offenders responded by forcing the victim to electronically transfer $1000 to Kirkwood and to withdraw a further $1000 in cash, which he gave to Banks.

Banks' barrister, Steven Whybrow, said on Tuesday that Kirkwood had played a more serious role in the criminal enterprise than his client.

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Mr Whybrow said Kirkwood had "played on" the fact Banks was, like the target of the apparent hit, nicknamed "Jimbob" and used it as a ruse "to get back-up".

The barrister told the court Banks became involved in the offending "to find out what was happening" because he feared he might be the "Jimbob" in question.

It transpired that he was not, Mr Whybrow said, and Banks ended up providing "sucker support" for Kirkwood as the extortion unfolded.

Mr Williamson expressed astonishment at claims Banks only accompanied Kirkwood to the Chapman house because of confusion around his nickname.

"[Banks] is saying, effectively, he thought he might be the subject of a contract murder, and his reaction is not to go to the police and seek safety or refuge, but to go along with one of the people who is contemplating carrying out the murder, simply to see what is happening," the prosecutor told the court.

"With respect, that is ridiculous."

Mr Williamson, who went on to describe this story as "utterly unreasonable", also said the victim "had to start a new life in Victoria" after the incident because he was having trouble sleeping and no longer felt safe in Chapman.

After hearing submissions, Justice Geoffrey Kennett said he wanted to give the case "proper thought".

He will sentence Banks, who is on bail, on a date yet to be fixed.

The same judge recently sentenced Kirkwood to five years, nine months and 15 days in jail over the extortion plot and various unrelated offences.

Another person involved in the extortion, Keona Rosalie Watson, was given a partially suspended jail term and placed on a drug and alcohol treatment order in May.

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