Leading Canberra barrister Jack Pappas says prosecutors barely have a 50 per cent chance of securing convictions, with some charges "doomed to fail" and others plagued by "insuperable difficulty".

Mr Pappas made those comments in written submissions tendered to the ACT Magistrates Court on Wednesday during an unsuccessful bid to have the 26-year-old woman released on bail.

The defendant, who cannot be named for legal reasons, has been behind bars on remand for just shy of two months.

She has pleaded not guilty to two counts of attempted murder, two counts of inciting murder and single charges of burglary and theft.

Police allege that the 26-year-old burgled her parents' home in late September and used her mother's laptop to access bank accounts and steal $15,000.

In the following days, she allegedly purchased more than $6000 worth of Bitcoin and began corresponding with a person known only as "Juan" on a dark web marketplace named The Sinaloa Cartel.

She is accused of ordering the murders of her parents through the website, allegedly providing their names and ACT address in a message that said: "Willing to pay $20,000 AUD to have this done as soon as possible. 2 individuals, death by accident if at all possible."

The woman was allegedly motivated by financial gain, with court documents revealing she stood to inherit more than $2.5 million from her parents' estate if they both died.

Police claim "Juan" agreed to facilitate the order, but the defendant provided only about $6032 worth of Bitcoin and failed to respond to messages asking for the balance.

The woman's parents were never harmed and detectives believe they would not have been killed even if $20,000 had been forked out.

Investigators have formed a view that the dark web marketplace was likely set up by scammers who had no intention of providing murder-for-hire services.

Police and prosecutors are still working to compile a brief of evidence, and Mr Pappas said they would currently struggle to prove the charges in a case "wholly unique and foreign" to Australian courts.

"The defendant says that the prosecution case on all counts is at best weak, beset with flaws both legal and factual, and can barely be described as enjoying better than 50/50 chances of success," he wrote in his submissions on bail.

Mr Pappas said the burglary charge was "doomed to fail" because, while the woman did not live in the family home, she had never been excluded by her parents and had a set of keys.

He used similar language in relation to the theft allegation, saying the $15,000 had merely been moved from one bank account to another, to which both the defendant and her mother had "lawful access".

Turning to the more serious charges, Mr Pappas wrote that there appeared to be "a fundamental lacuna in the prosecution case".

He said the dark web correspondence between "Juan" and a user alleged to be the defendant appeared to show "Juan" making an offer to the defendant, who, in contractual terms, never accepted it.

Mr Pappas also highlighted that the messages were all from September 24 last year, and said there was no suggestion the defendant had concluded a proposed contract with "Juan" or any other person before being arrested about two-and-a-half months later.

He predicted that the prosecution would be unable to prove beyond reasonable doubt that the defendant had done anything "more than merely preparatory", or that she had intended for a murder to be committed.

The prosecution therefore faced "an insuperable difficulty", he wrote.

The defendant's case is next expected in court on March 1.

Any trial is set to be at least a year away, however, with police waiting on the outcomes of complicated requests for evidence from overseas sources.