'No reason to murder my sister': Doveton killer had a 'knife obsession'

A Victorian woman's killer has been revealed as a butcher with a knife obsession.

Rani Featherston was stabbed more than 20 times just around the corner from her Doveton home in 2014.

Her murderer pleaded guilty but has never given a reason why he carried out the attack.

Rani Featherston was stabbed 21 times. Photo: 7 News

More than three years on from her murder, the motive remains a mystery.

The defence said the murder was a result of the killer's troubled personal life.

Killer Christian Bain-Singh had a 'troubled personal life'. Photo: 7 News

Christian Bain-Singh had lost his job, broken up with his fiancé and was about to lose his house when he ran into Ms Featherston in the early hours of April 2, 2014.

The pair had met only once before, some months before when they had argued about his dog.

"He doesn't have a good enough reason to murder my sister, no reason is good enough," Rani's brother Aaron said.

'No reason is good enough': Rani's younger brother Aaron. Photo: 7 News

While at the crime scene, Bain-Singh bragged about what he had done on Facebook, writing: "It's not the size of the dog in the fight, it's the size of the fight in the dog".

Eleven days earlier he had stabbed a man in an aggravated burglary with the same kind of knife, in a crime motivated by his drug addiction.

The 23-year-old pleaded guilty to three charges including murder after making several admissions to his friends, prostitutes and an undercover police officer he shared a cell with.

Bain-Singh boasted about the murder on Facebook. Photo: 7 News

The court heard that Bain-Singh worked as a butcher and had been obsessed with knives since he was a teenager.

He was regularly seen playing with knives - even while reading a book.

Bain-Singh will be sentenced next month.

Ms Featherston's younger brother said he planned to be there to stare down the killer.

'He's taken my world away from me', Rani's brother Aaron said. Photo: 7 News

"I love Rani very much and he's taken my world away from me," he said.