THE killer ex-boyfriend of Adriana Donato has been jailed for 19 years for her calculated and sinister murder.

Justice Michael Croucher wiped tears from his eyes and appeared to become overcome with emotion as he sentenced James Stoneham in the Supreme Court today.

Stoneham, 22, sat stony faced as Justice Croucher read details of the cold-blooded and "calculated" murder to the court.

He described the fatal stabbing murder of Ms Donato as a "particular serious and sinister example of murder" that was aggravated by the weeks of planning that preceded the killing.

"It is disturbing that only a day before her murder Mr Stoneham told (a doctor) he had no thoughts of hurting anyone," he said.

"He has done a horrible thing and must be punished accordingly."

Stoneham's visibly distressed parents Julie and Alan, a former VFL footballer with Footscray and Essendon, sat just metres away from their son during the hearing.

In a show of support for Ms Donato dozens of her family and friends filled the Supreme Court.

Justice Croucher imposed a non-parole period of 14 and a half years.

Earlier, the heartbroken family of Adriana Donato say she would still be alive had friends taken seriously her ex-boyfriend's threats to murder her.

Stoneham spoke openly to friends about his plans to murder the bubbly 20-year-old student.

He even showed one the knife with which he intended to stab her.

But no one warned her of his cold-blooded plans, leaving Stoneham free to lure his unwitting victim into his trap.

After weeks of plotting his evil deed, he drove her to an isolated park and killed her.

Her family hoped justice was served for the girl who was just weeks away from embarking on adult life with a science degree from Melbourne University, her 21st birthday, and the trip of a lifetime.

Prosecutors earlier called for a jail term of up to 21 years.

But Stoneham's lawyers asked the Supreme Court to consider an "unusually light'' sentence with a non-parole term as low as 11 years.

Stoneham pleaded guilty to the murder at Aberfeldie on August 23 last year.

Ms Donato's devastated mum, Grace, told a pre-sentence hearing earlier this month: "Christmases and birthdays will never be the same again.

"Adriana was very caring, loving, and thoughtful, and always ready and willing to help out others,'' she said.

"She had a beautiful soul and an infectious smile. Nothing was ever too much trouble for her, as she had a happy-go-lucky attitude to life.''

"Adriana could immediately see her place in the world, as an environmental scientist helping nature recover from mankind's influence,'' dad Giuseppe told the court.

"What a fantastic future it would have been.''

Ms Donato had started work with the Wilderness Society.

She had been about to embark on a holiday of lifetime, visiting family in Italy - where she planned to do an intensive language course - before flying to Berlin to meet up with her best friend for New Year's Eve.

"She could have gone in any direction," cousin Pat Panetta said.

"She was excited about working in environmental science, tackling climate change and saving the planet."

Ms Donato had begun dating Stoneham, the son of VFL player Alan, while studying at Penleigh and Essendon Grammar, but they broke up in December 2011.

Stoneham's life then spiralled out of control. He developed severe depression and tried to take his own life.

But in the end, he took Ms Donato's.

shannon.deery@news.com.au