A Victoria man who killed a woman and set her daughters on fire in 2010 blames his tragic childhood for the crimes he committed.

Sean Marafko, 42, is charged with murdering 29-year-old Joanne Wicking and assaulting her two daughters, then aged 10 and 8. He was released on parole from a Queensland jail in late September.

In a pre-sentence plea hearing before Victoria Supreme Court Justice Elizabeth Curtain on Friday, Marafko's lawyer disclosed that his mother was a prostitute and both parents were drug addicts.

Although Marafko was removed from his parent's home when he was 2 years old because of physical abuse such as burns and broken arm, he continued to suffer from physical and sexual abuse from his adoptive parents.

He was kicked out of school at Year 7 and worked in a bakery when he was 16 as an apprentice. The lawyer said that Marafko is married and has two adult sons whom he had not seen since 1998.

Marafko stabbed Wicking four times, once in the heart, and battered her face and head. She was found dead in her bathroom, with the knife found in the bath. He was staying with the Wickings through a friend's arrangement after he was temporarily released for previous violent offences.

Two of her daughters witnessed the crime and then were assaulted by Marafko. He then used an ignited aerosol can to burn the 8-year-old girl. While he was attacking the family, Marafko ordered a third Wicking girl to get two of her younger sisters in another room, but she escaped and was found by neighbors running down the road in her underwear with her mouth taped.

Marafko pleased guilty in late 2010 to one count of murder and two counts of intentionally causing serious injury. The Victoria Supreme Court continues the hearing.