Leo Nicholas Eliadis, 47, and Nick Parlov, 24, are on trial in the ACT Supreme Court accused of planning and carrying out the attack, which was captured on dramatic surveillance footage.

In his closing statement to the jury on Wednesday, prosecutor Trent Hickey said both accused had lied and denied knowing each other, although officers had been intercepting their conversations.

Mr Hickey said Mr Eliadis lied when he told police his car had been damaged in January, in what the Crown says was an attempt to distinguish his Honda CRV from the car captured on surveillance video leaving the scene just after midnight on March 13, 2014.

Police had in April photographed his car with no damage.

Mr Hickey said Mr Parlov lied too when he said it wasn't him in footage when he went meet Mr Eliadis at the Belconnen Westfield, and he lied when he said it wasn't his voice on the tapes.

The prosecutor said these lies showed consciousness of guilt.

Prosecutors have tried to prove Mr Parlov was the figure in the green hoodie in surveillance footage of the arson, while Mr Eliadis, if not the driver of the green Honda, was involved in its planning.

Both have denied the allegations and pleaded not guilty.

The Crown case against the two men was circumstantial - there was no "smoking gun" - and it had come down to hard and crafty police work, the prosecutor told the jury on Wednesday.

Mr Hickey's closing also detailed the evidence that he said pointed to the pair's guilt, and asked the jury to take it all into account

Mr Eliadis, the godson of a cafe owner nearby, was the only green Honda CRV owner in Canberra with links to the Weston area.

There was a four-second phone call between Mr Eliadis and Mr Parlov about 9.40pm the night of the arson on March 12.

Mr Parlov's ex-girlfriend said Mr Eliadis had picked up Mr Parlov to do a "job" one night in early 2014. She said he had returned with a green hoodie she'd never seen and he told her Mr Eliadis gave it to her and he had to destroy it. She next saw it ripped to shreds.

Mr Hickey asked the jury to consider the intercepted phone calls and conversations between Mr Parlov and Mr Eliadis, in which they spoke about "paper" and how much was owed to Mr Parlov.

"The only conclusion is that each accused participated in a joint criminal enterprise [to commit the arson]," the prosecutor said.

Mr Eliadis' lawyer Theresa Warwick suggested Mr Eliadis had not denied knowing Mr Parlov, but instead said he knew many Nicks, but not many last names. He may have been mistaken about dates, including for the damaged car when interviewed months later.

She said police had listened to thousands of his conversations, but the jury only heard an "infinitesimally" small number, those few which detectives suspected related to the arson. There may well be an innocent explanation for the ones played, she said.

She challenged the jury to question police conclusions it was a green Honda CRV at the scene of the arson, she said, a conclusion pieced together from two surveillance cameras - one black-and-white - at different times, and based on assumptions and timings.

"It's very hard to see in the grainy CCTV footage any detail of the vehicle at all," she said. "I just ask you to look very carefully."

Mr Parlov's barrister Richard Davies called the case in relation to his client "extremely tenuous", noting the lack of eyewitnesses or forensic evidence such as fingerprints or DNA.

"The circumstantial evidence you heard is equally consistent with Mr Parlov's innocence," he told the court.

Mr Parlov helped out with renovation work for Mr Eliadis, he said, which would explain why he may have been asking for money.

The barrister noted the man's relationship with his ex-partner had ended badly and asked the jury to consider if she was angry enough to lie to get Mr Parlov in trouble.

The jury will retire to consider its verdicts on Thursday.