Sex worker advocates have expressed their "rage and sadness" after a man who was due to face a double-murder trial for killing two women struck a manslaughter plea deal with Victorian prosecutors.

Xiaozheng Lin, who killed sex workers Yuqi Luo, 31, and Hyun Sook Jeon, 51, in late 2022, struck a deal with prosecutors in July, the Supreme Court of Victoria heard on Monday.

Lin killed Ms Luo in her Melbourne CBD apartment on La Trobe Street on December 27, 2022.

He later went to the Docklands apartment of Ms Jeon, where he "committed an "unlawful and dangerous" act which caused her death.

The standard sentence for murder in Victoria is 25 years with a maximum of life in prison, but having pleaded guilty to manslaughter, the 24-year-old Chinese national now faces significantly less jail time.

Gia Green, the manager of Victorian sex worker organisation Vixen said she felt "a lot of rage and sadness" about the deal.

"I think for sex workers, it leaves us angry … when we see things like this, it really undermines [our] advocacy," she said.

Bee Charika, who is Vixen's CALD and migrant peer project worker, said the result was "disappointing".

"This has created feelings of fear and deep loss among the Asian migrant sex worker community in Victoria," she said.

"We live in a society that does not respect Asian migrant sex workers but we deserve justice and to be safe at work like every other worker."

Former MP believes deal risks sending 'terrible message' about value of women's lives

Fiona Patten, former Victorian upper house MP, said she believed the decision reflected the stigma faced by sex workers in society.

Ms Patten led the Victorian parliamentary review which resulted in the two-part decriminalisation of sex work in 2022 and 2023.

"There is still considerable judgement around women who choose to do sex work, at all echelons of our society," she said.

Ms Patten said the deal not only sent a poor message to sex workers, but to women in general, and called for more education within the justice system.

"Violence against women is only escalating, and seeing deals like this done will not change that," she said.

"I think it sends a terrible message about the value society puts on the lives of sex workers, and women in general."

In a brief statement, a spokesperson for the Office of Public Prosecutions (OPP) said the decision to accept Lin's pleas of guilty to manslaughter "was made after careful consideration of the evidence in the case and in accordance with the Director's Policy".

Balancing 'public interest' of plea deals is a complex task

According to the OPP website, the defendant's legal team contacts the office to let them know their client is willing to plead guilty to certain charges.

The OPP then weighs up whether accepting this deal is in the "public interest", which includes looking at the strength of the evidence, the nature of the charges and the views of the victim, among other considerations.

Speaking in general terms and unrelated to Lin's case, University of Melbourne law professor Jeremy Gans said a key consideration for the prosecution was whether a lesser charge "suffices to do justice".

Professor Gans said there were potential benefits for victims if a plea deal was taken, as they would get a definite result and would not have to endure a trial.

But he said there could also be downsides. While victims are consulted by the prosecution when they're considering a plea deal, they do not necessarily get to decide what happens.

"The evidence that matters to them may not get aired and they may want the accused to face the more serious charge," he said.

Professor Gans said the bargaining process was essential to the justice system.

"It would be very expensive to go to trial on every case, even every serious case," he said.

"But there are costs to justice too — the prosecution and defence evidence is never tested by a court and the public may worry that the outcome doesn't reflect the defendant's criminality."

Each manslaughter charge carries a maximum of 25 years, and if standard sentencing practices are followed, Lin will serve a bulk of his sentence concurrently.

However, the median imprisonment sentence for manslaughter is much lower than murder, according to the Sentencing Advisory Council.

In the five years to 30 June 2023, the median murder sentence in Victoria resulted in 23 years' imprisonment, compared to nine for manslaughter.

It is expected Lin will be sentenced within the next fortnight.