Murdered woman's boyfriend shares his grief in court

The pair were briefly co-workers but he began harassing and stalking her after she turned him down romantically.

On the night before her death, Ms Manno posted a photo of her boyfriend Christopher Ridsdale for the first time on Instagram.

Family and friends have shared their grief in court at the passing of Ms Manno. (Diego Fedele/AAP PHOTOS)

A few hours later, Sako broke into her bedroom while she was sleeping and killed her.

Mr Ridsdale was among the family and friends who read statements to the Victorian Supreme Court on Tuesday, each sharing their grief at the passing of Ms Manno.

"Every day without Celeste is a reminder of what we should have had together," Mr Ridsdale told the court.

"This crime has changed my life, this crime has robbed us of a future.

"I've lost my beautiful Celeste and nothing will ever change that."

Ms Manno's friend Sarah Pervaiz also confronted Sako, calling him selfish, apathetic and inhumane.

"I know there is nothing I could have done but it doesn't stop the immense feelings of regret," she said.

"No sentence will ever be enough but I would hate to see the system fail Celeste again."

Sako has pleaded guilty to Ms Manno's murder but argued he only caused two of her 23 stab wounds. (Diego Fedele/AAP PHOTOS)

Sako has pleaded guilty in the Victorian Supreme Court to Ms Manno's murder but he's argued he only caused two of the 23 stab wounds.

Sako, representing himself, claims the other injuries came from the bedroom window's broken glass.

During the first day of the plea hearing on Monday, Ms Manno's mother, father, brother and aunt read out statements to the court.

Aggie Di Mauro, Ms Manno's mother, confronted Sako and called him a coward and a beast for taking away her daughter.

"Celeste had no interest in him and he couldn't accept that," she told the court.

"We thought she was safe and sound asleep in her bed."

The hearing before Justice Jane Dixon continues.