Christopher Allen Bell strangled his girlfriend in a Melbourne laneway, then instead of calling for help he went to Crown Casino to gamble and then home to bed.
Natalina Angok's relatives described the 32-year-old as the light of her family, a sweet soul with a heart of gold.
She had been in a relationship with Bell for nine months before he killed her and left her body in a Chinatown laneway.
Bell, now 34, was on Friday jailed for 21 years for her murder.
He had a history of violence against his partners and told a pre-sentence hearing last month he was in the midst of a "psychotic meltdown".
Ms Angok began to feature in his schizophrenic delusions almost immediately after their relationship began.
Bell reported visual and auditory hallucinations in the lead-up to the murder, and had admitted himself to hospital a week before.
He said his mother had tried to have him sectioned to remain in hospital, but they wouldn't because he had admitted himself. He was released to a transition facility which he then voluntarily left.
He was still experiencing hallucinations - the voices of Ms Angok and a former partner who had died.
"We just want to kill you," he said one of the voices told him.
While Bell was diagnosed with schizophrenia in 2014, he was not treated with anti-psychotic medication after his hospital admission.
He saw Ms Angok several times in the days after his release. Just after 5am on April 24 last year they argued as they walked through Chinatown, after Bell was caught trying to steal a bottle of wine from a liquor store.
Ms Angok went down the laneway to relieve herself, and he said he wondered if he should follow to "keep an eye on her".
"Things sort of went a bit funny and then I remember being on top of her and panicking, not really knowing what was what I was doing or how I even ended up on top of her," he said.
Bell later told police he had "choked the life out of her until she breathed no longer". Her body was found about 90 minutes later.
Ms Angok fought back. His DNA was found under her fingernails, from scratches on his face.
"Having killed her for reasons you yourself cannot comprehend, you left her alone and dead in an alleyway," Justice Lex Lasry said.
Bell had claimed he was immediately remorseful for what he had done, but he did not seek help for Ms Angok.
Instead he spent an hour gambling at Crown Casino, stood on a street corner eating a souvlaki for 15 minutes, and bought a bottle of wine and cigarettes before going home to bed.
Doctors found Bell, whose mental health has stabilised in prison, remains a high risk of reoffending.
Angok's sister said she would never forgive Bell.
"You were supposed to love and protect her ... even if my life depended on it, I will never forgive you," she said.
Bell will be eligible for parole in 2034.
