A serial killer convicted of 10 murders says having a non-parole period in his sentence would "greatly assist" his "mental wellbeing" and allow him time to spend with his adult son.

Key points: Snowtown killer Robert Wagner applies for a non-parole period to be set

Snowtown killer Robert Wagner applies for a non-parole period to be set He wrote a letter to the Supreme Court

He wrote a letter to the Supreme Court If a non-parole period is set, he would still have to apply for parole once it ended

The letter, written by Snowtown killer Robert Joe Wagner to South Australia's Supreme Court, has been released as part of his application for a non-parole date to be set.

In it, he wrote that he was the "father of a 21-year-old son".

"I have been in custody since he was 18 months old and would very much like the chance to spend time with him in the community," he wrote.

"I believe that by having a non-parole period set this would greatly assist my mental wellbeing.

"Even if the non-parole period was lengthy just having a date would be beneficial for me."

Wagner was sentenced to life imprisonment without parole in 2003 for his role in the "bodies-in-the barrels" killings, which were committed during the 1990s.

During the trial the court heard gruesome detail about his crimes, including that he and John Justin Bunting had cooked the flesh of one of the victims.

The remains of eight victims were found in six acid-filled barrels in a disused bank vault in the small town of Snowtown, north-west of Adelaide, in May 1999.

Wagner and Bunting benefited financially from their crimes by claiming the social security benefits of some of their victims.

Robert Wagner's letter asking for a non-parole period. (Supplied)

Claim of good behaviour in prison

In the letter, Wagner wrote that his behaviour in prison had been "reasonably good" and that he was in a trusted position working at the prison.

"I am eager to continue with my good behaviour so that I can progress through the system [and] as part of this process having a non-parole period set would be beneficial," he wrote.

The building where the bodies were found is no longer a bank. (Facebook: Michael Margot)

Under South Australian law, a prisoner without a parole period can apply to the sentencing court to set one, but the court can decline to do so if it believes it would be inappropriate for reasons including the gravity of the offence.

The hearing will be held on Monday.

Parole still not guaranteed

If the court does decide to set a non-parole period for Wagner, he would then have to serve that term and then apply for parole through the South Australian Parole Board.

SA Parole Board presiding member Frances Nelson QC said factors in deciding if a prisoner was suitable for parole included the potential risk of reoffending, the behaviour of prisoner, if he or she was rehabilitated and the impact on any victims.

"The Parole Board doesn't release prisoners unless we believe they are not going to present a risk to the community," Ms Nelson said.

"We take our job very seriously — it is a difficult thing predicting future behaviour, but we always have to do it when we make that decision."

SA Commissioner for Victims' Rights Bronwyn Killmier described Wagner's crimes as "horrendous".

"It affects the families forever, they feel the pain and suffering even though it was some time ago, the trauma is real for them," she said.

Premier Steven Marshall dismissed claims Wagner could walk free in the near future.

"Robert Wagner is not applying to be released from jail," Mr Marshall said.

"He will be in jail for a very long period of time — he's not getting out anytime soon."