Prime Minister Anthony Albanese may have prejudiced a criminal case against Cassius Turvey's alleged killer by publicly labelling the tragedy a murder, legal experts fear.

Mr Albanese's office has refused to reveal whether the Prime Minister sought legal advice before using the term during a televised press conference on Wednesday.

The 15-year-old Noongar boy was allegedly attacked with a metal pole on his way home from school in WA last month, succumbing to his injuries ten days later.

A 21-year-old Perth man has been charged with a host of offences, including murder, over the death, which has sparked a national outcry over the disproportionate violence faced by First Nations Australians.

Legal experts are warning politicians inserting themselves in ongoing cases for "political mileage" can inadvertently hurt victims by preventing trials from proceeding.

Asked about the death on Wednesday, Mr Albanese told reporters Cassius had been "murdered" in an "extraordinary, just terrible fashion", despite the matter not yet having gone before court.

The Prime Minister's Office declined to offer any explanation when approached for comment by The Canberra Times.

But Katherine Dowling, senior lawyer at WA law firm Curt Hoffmann & Co, warned the comment could "absolutely" undermine the chance of a fair trial.

"It does no one any favours, and really it's effectively buying political mileage by making comments on matters which are probably properly dealt with by the court system," she said.

"It's not a political football."

Ms Dowling was one of thousands of Australians who attended vigils held for Cassius across the country, including in Canberra, on Wednesday evening.

She said Australia had a "very, very good [criminal] system" based on the assumption of innocence, which must be allowed to run its course.

That included politicians, particularly senior ministers, being "as dispassionate as possible" when commenting on ongoing cases, to ensure victims can receive justice.

"They don't get any closure if the accused person is unable to get a fair trial. It's a terrible situation," she said.

"I utterly and totally feel for [Cassius' mother] ... It's horrific. But the rules exist for a really good reason: to help the victims as much as the accused person."

In an appearance on The Project later on Wednesday evening, Mr Albanese tempered his language and did not refer to the death as a murder.

"Of course, the processes have to continue, but this just a real human tragedy that has impacted so many people," he said.

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His predecessor Scott Morrison faced criticism in February for publicly apologising to Brittany Higgins, who was allegedly raped by a colleague in Parliament House, for the "terrible things which took place here".

Lawyers for Bruce Lehrmann, the man accused of raping Ms Higgins, argued the comments had prejudiced their client's chances of receiving a fair trial, and attempted to permanently stay the case.

The case did eventually go before the court, but a mistrial was declared after jury misconduct was uncovered.

"I think we arguably have the best and fairest system in the world. But the Higgins trial is a demonstration that when people speak out of turn, human nature will prevail," Ms Dowling warned.

Jason Bosland, an expert in communications law at the University of Melbourne, said "the ultimate test" was whether the jurors were influenced when the jury was formed, something which was not always "black and white".

The fact Mr Albanese made the comment well before a possible trial meant it may be less prejudicial, but his status as prime minister could make it more so, he said.

"There's a sort of fade factor there. Will jurors remember that Anthony Albanese actually said this? Probably not," he said.

"[But] when something's said by someone in a position of authority, there's a chance that it might make a greater impression on potential jurors."

Professor Bosland said he "can't see" any public interest defence arising from the comments, warning politicians against commenting on ongoing criminal proceedings.

"I do think they have a responsibility not to comment on cases that are currently before the courts, particularly criminal cases where there's a jury involved," he said.

Treasurer Jim Chalmers was more circumspect than his leader on Thursday, saying "the thieving of a young life with so much promise, I think, impacts us all".

"We will go further on that journey if we walk together. When horrific things like this happen, it is a reminder that we've got much more to do," he said.

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