Borce Ristevski's "manifestly inadequate" sentence for killing wife Karen has been appealed.

— With AAP.

An appeal against wife-killer Borce Ristevski’s jail term has been lodged by Victoria’s Director of Public Prosecutions.

Kerri Judd QC on Monday announced she had lodged the appeal on the basis the sentence is “manifestly inadequate”.

In April, 55-year-old Ristevski was jailed for at least six years and a maximum of nine years after admitting to the manslaughter of his wife Karen Ristevski, meaning with time already served he could walk free from prison on parole in December 2023.

A Court of Appeal date is yet to be set.

Karen Ristevski’s body was found covered in branches at Macedon Regional Park eight months after the 47-year-old went missing in June 2016.

Ristevski killed his wife at their Avondale Heights home before bundling her body into her Mercedes-Benz. He lied to his wife’s family for months and played a mournful pallbearer at her funeral.

Mamamia’s daily news podcast The Quicky speaks to Channel Nine court reporter Eliza Rugg about why Karen Ristevski’s life was only worth nine years. Post continues below audio.

He was initially due to stand trial for murder but a court deemed there was insufficient evidence to secure a conviction, at which point he pleaded guilty to the lesser charge of manslaughter.

The son of Borce Ristevski, Anthony Rickard, has claimed his father pleaded guilty to the manslaughter of his wife Karen Ristevski to avoid details of his wife’s relationship with his son coming out in court.

Ristevski, 55, pleaded guilty last month to the manslaughter of his wife Karen almost three years after she went missing in June 2016.

“I gave him an ultimatum,” Mr Rickard told news.com.au at the time.

“I told him ‘If you don’t get up and be a man I’ll go into the (witness) box and tell them exactly what went on behind closed doors’.”

Rickard, Borce Ristevski’s son from a previous marriage, had repeated earlier claims that he and his stepmother had a sexual relationship.

He said his father knew of their relationship for years after he first approached him about it in 2006, but his father “did nothing” and “didn’t protect me”.

An autopsy could not determine the cause of Karen’s death and Ristevski has never provided a description of how his wife of 27 years died.

Ristevski had always been the prime suspect in her death, a fact he continuously and vehemently denied for two years, lying to police, family, friends and his own daughter, until the eve of his high profile murder trial.

The couple's daughter, Sarah, has supported her father throughout the ordeal, providing a glowing reference for him in March at his pre-sentence plea hearing.

“The love they had for each other and the marriage that they shared is something I hope to one day experience myself,” the 23-year-old wrote in the document submitted to the Supreme Court of Victoria.

“Growing up as a family, my mum, dad and I were completely inseparable… the love we had for each other was unexplainable,” the reference read.

"It pains me inside to hear all of these untrue claims about my parents [sic] marriage and the love they had for each other from people who were not apart [sic] of their lives."

Ristevski could have been jailed for up to 20 years for manslaughter.

For more on this topic:

• The reason behind the sentence: What the public didn't see about Borce Ristevski's trial.
• There's a woman's life we must never forget: Karen Ristevski's.
• "I saw it in his eyes": Borce Ristevski's son claims he knows how his stepmother was murdered.