Nanette Rogers SC told the Supreme Court of Victoria on Tuesday that the Crown didn't want to see Todd jailed for life, even though she claimed he'd "stalked his prey" and killed her to satisfy a macabre sexual fantasy.

Todd, who enjoyed strangulation and snuff porn, murdered Ms Dixon to realise a long-held sexual fantasy of violent rape culminating in a female's death, she argued.

In "chilling" post-murder behaviour, Todd even searched Google on his iPad for violent, strangulation pornography and "emo girls", just hours after he'd murdered the 22-year-old.

But Dr Rogers also argued the mildly autistic 20-year-old, who has since been diagnosed with sexual sadism disorder, shouldn't be imprisoned for life.

"A non-parole period is appropriate due to his age, his lack of prior convictions and his willingness to plead guilty at a very early stage," Dr Rogers told Justice Stephen Kaye on Tuesday.

"We're not saying Your Honour cannot give him a very lengthy head sentence and non-parole period."

Justice Kaye previously indicated he would consider imposing the maximum sentence - life without parole - if he found Todd premeditated the murder.

Todd, dressed in a grey button-up shirt and grey jeans, sat with his eyes downcast throughout Tuesday's hearing, which was a final chance for lawyers to make submissions before he is sentenced later this year.

Dr Rogers argued that Todd premeditated his murder of Ms Dixon, who he attacked as she walked home barefoot through Princes Park on June 12 last year after stalking her for almost an hour.

She said Justice Kaye should reject Todd's claims that he left Ms Dixon "unconscious" in the park and that his decision to kill - rather than rape alone - was "impulsive".

"There was always a sense of control and power, and it always culminated in the death of the female," she said of Todd's depraved fantasies.

"He intended to hurt her and he knew he was hurting her."

Justice Kaye said if Todd's motive to murder was to satisfy a sexual fantasy, "then that elevates this case to one of the very highest order".

Defence barrister Tim Marsh argued it was impossible to know when Todd decided to murder Ms Dixon, saying the killer didn't know if he was capable of completing his fantasy.

"He didn't know how far he would take it," Mr Marsh said.

"This is a most difficult case. It will take a bit of time for me to think about," Justice Kaye said before adjourning the plea hearing for sentencing at a later date.

Australian Associated Press