Isaac Costa’s brutal murder of girlfriend Anastasia Slastion after night at Greystanes

A possessive boyfriend’s brief but violent relationship with a woman escalated after she refused to dance with him. Hours later he bashed her to death during an “11 out of 10’’ drunken rage in Sydney’s west.

Anastasia Slastion was killed at the hands of her boyfriend Isaac Costa. Picture: Facebook

An attention-seeking boyfriend’s brief but violent relationship with his girlfriend escalated after she refused to dance with him at a western Sydney pub hours before he murdered her.

The brief but rocky relationship between Isaac Costa and Anastasia Slastion has been exposed in NSW Supreme Court documents after the 30-year-old murderer faced arraignment on Friday.

Police found Anastasia Slastion’s slain body lying on the bed of the Brighton St granny flat behind his parents’ home on February 25, 2023 – a mere six weeks after they met at a bar in the city.

Just hours earlier, the pair visited Greystanes Hotel where they ran into a mutual contact, whom Ms Slastion spent a lot of time with, much to Costa’s frustration.

“He won’t leave me alone,’’ the 32-year-old victim told her friend.

Anastasia Slastion was murdered at the hands of her boyfriend Isaac Costa. Picture: 9News

“He is always needing attention.’’

Costa’s jealousy grew when his Russian national girlfriend rejected him on the dance floor, preferring to dance with the woman who asked him “what the hell is going on?”

Isaac Costa was highly drunk when he bashed his girlfriend.

Costa questioned why the woman was trying to get involved in their relationship before she expressed concerns for Ms Slastion’s safety.

“Don’t go home with him,’’ agreed facts revealed the woman said.

“Are you going to be all right?’’

An Uber driver who drove them home from the pub also witnessed an argument between Costa and Ms Slastion, who sniped at him to “f--k off” after she complained he didn’t let her dance.

Anastasia Slastion spent her last hours at the Greystanes Hotel. Picture: Angelo Velardo

“This is not the first time you do this to me,’’ she said.

“You are always doing this to me.’’

Ms Slastion, who only arrived in Australia on a working visa four months before her homicide, threatened to end their relationship during the Uber ride.

Their argument continued once they arrived home, with the victim shouting at Costa to “open the f--king door”.

She was soon dead.

Just before midnight, Costa delivered fatal blows to her, punching her head and “by applying pressure to her neck”, documents state.

During a phone call to a friend, he said “I was at the pub with my girlfriend and she had gone off with some other guy (or girl).’’

The friend rushed to the granny flat and saw the victim’s limp body on the bed.

Costa told another man who woke up when he found the lights of the granny flat on after midnight: “She started hitting me again and I lost it and I hit her back … I’ve been trying to resuscitate her but I can’t.

“I didn’t mean to hit her, I just lost it and I snapped.’’

Police at the Brighton St home on February 25, 2023, after Costa’s arrest. Picture: Julian Andrews

With blood on his shoulder and forehead he confessed to the brutal crime.

“I killed Anastasia, I’ve bashed her to death,’’ he told the man.

Crying and apologising, Costa positioned himself over the victim’s dead body on the bed to perform chest compressions.

He went to his parents’ adjacent demountable home, declaring he wanted to kill himself.

When police arrived, “two elderly people” were trying to wrestle Costa to the ground, prompting the officer to deploy a Taser and handcuff him.

Costa rated his level of intoxication as “11 out of 10’’ when police asked him to describe how drunk he was. He had knocked back six short glasses of Jim Beam and Coke and seven of the same alcohol in tall glasses.
He had scratch marks on his neck and his right hand was swollen over his knuckles.

Facts reveal their relationship, which was intimate immediately after they met, was marred with plenty of red flags.

Documents state weeks before Costa murdered his girlfriend, he unleashed a flurry of text messages abusing her.

“I love you so much and you shit on me you’re a disgrace,” he wrote.

“Even b--tches don’t act like that you should be ashamed of yourself. F--k you. F--king child.”

He apologised later that day, saying he wrote that “all that in drunkness (sic)’’.

A week after the fatality, police seized a three-page Valentine’s Day letter in Ms Slastion’s Surry Hills home where a Michael Hill jewellery gift bag was also found.

The letter gushed over his “beautiful”, “smart” and “funny” partner but he also apologised.

“I never meant to hurt you. I only ever wanted to love you,” he wrote.

Costa pleaded guilty to murder in May and is due to return to court for a sentence hearing on December 12.