The family of a student who was killed in her bed believe a picture of her touching her boyfriend pushed an alleged stalker over the edge and into a stabbing frenzy.
Melbourne woman Celeste Manno, 23, was found dead in a home at Mernda, to the city's northeast, at about bout 4.10am on Monday.
Suspect Luay Sako, 35, is under police guard in hospital after handing himself in following her death.
In an emotional tribute, Ms Manno's brother Alessandro shared his disappointment that he was unable to protect the 'beautiful' and 'loving' young woman.
Ms Manno's family think a picture of the 23-year-old and boyfriend Chris Ridsdale linking arms likely triggered the alleged attack.
Celeste Manno's family think this picture of the young woman and her boyfriend Chris Ridsdale linking arms likely triggered the alleged attack
Pictured: Suspect Luay Sako, 35, is under police guard in hospital after handing himself in following her death
She shared the photo to social media on Saturday night and it was the first time she posted with a man since the alleged harassment begun, The Herald Sun reported.
Her 19-year-old brother Alessandro said: 'It was like if he couldn't have her, no one could.'
Alessandro remembered his sister in a Facebook post on Wednesday.
'I am in tears writing this right now and there is never gonna be a perfect way to say this, but to my beautiful and amazing loving caring sister Celeste, you were my everything,' he wrote.
'You were my sister, best friend, and most importantly the most amazing beautiful person in my life and I can't believe your gone and I can't hug you and can't kiss you every day after work.
'I need you so much Celeste and I need you to help us all get though this cause I can't do this by myself, I need you, mum needs you and all of our family needs you.'
Alessandro described his sister's alleged killer as 'cowardly'.
'He chose the one night in my life I was away from home for the night and couldn't been there to protect you like you always did for me,' he wrote.
Ms Manno (pictured) was studying at university and worked at a Serco call centre
On Wednesday, Alessandro paid tribute to his sister in an emotional Facebook post. The siblings are pictured together
Alessandro described his sister's alleged killer as 'cowardly'. 'He chose the one night in my life I was away from home for the night and couldn't been there to protect you like you always did for me,' he wrote
The Facebook tribute included numerous pictures of the siblings during happier times.
Ms Manno's devastated family faced the media outside their home on Tuesday and revealed the alleged killer was comforted by the young woman when he was fired 18 months ago.
Her father Tony was accompanied by sons Jayden and Alessandro and uncle Gabriel outside the family home where they described the alleged killer as 'evil'.
'She wasn't close with him at all, but just to give him some support she walked him out the door,' her brother Alessandro said, who refused to name him.
'Ever since that day he has been obsessed with her and harassing her over social media for months and months with like vulgar and disgusting messages.'
Alessandro (pictured with Ms Manno) said his sister was 'the most amazing beautiful person in my life'
The Facebook tribute included numerous pictures of the siblings during happier times
Ms Manno was employed at a Serco call centre and it's understood Sako previously worked in her team.
In March, the terrified woman was forced to file an intervention order against her alleged tormentor.
He disappeared that month, but the messages eventually started up again.
Tony Manno said the justice system had let his daughter down.
'It let my daughter down,' he said. 'And it's gotta be changed. It won't bring her back but it has to be changed.'
Jayden (left), Alesandro, Gabriel and Tony Manno, with baby Daisy, outside the home where Celeste Manno was killed on Monday
About a dozen friends joined Ms Manno's boyfriend in a footpath vigil to mark the awful tragedy
The abuse started about January where the alleged offender would bombard Ms Manno over Instagram.
'At first she would be nice to him and just say 'look thank you but I'm not interested',' Alessandro said.
'Then he became obsessive so eventually she had to block him and he created about a million other accounts until this happened. I hope justice gets served to him in more ways than one. I hope he rots.'
Alessandro said he had never gone more than two days apart from his sister in his entire life.
On the night she was killed, he had spent a rare evening away from the home.
'It was actually my first night away from home in my life. My first night ever in 19 years and it was the one night this happened. So I can only assume he planned it,' he said.
'I feel like she's going to come home from work any minute ... I don't know how we're going to get through it.'
A mourner laid a bouquet of flowers and cried out the front of Ms Manno's home on Monday
Ms Manno's boyfriend, Chris Ridsdale, was embraced by friends out the front of her family home in Melbourne's north on Tuesday afternoon
Celeste Manno's father Tony cradles baby Daisy and begs the Victorian justice system to change
The family remain unsure how Ms Manno's killer found out where she lived.
'He must have been stalking us,' Alessandro said.
The men paid tribute to Ms Manno, describing her love for her niece Daisy, whom was cradled by her father Tony.
'Celeste adored her. She was absolutely in love with her niece,' Tony said.
'Celeste was coming over tomorrow night to visit after COVID. COVID kept us all separated too long and little Daisy was really looking forward to seeing her.'
The family described their loved one's killer as 'evil'.
'It's harrowing. Such a senseless and unfathomable evil act,' Jayden said.
'It should never have