A relative of Mert Ney said family had been devastated by the killing of a young woman, confirmed they were not religious

A young relative of Mert Ney, who allegedly killed one woman and stabbed another in Sydney on Tuesday, has said she wants to “say sorry a million times” to his alleged victims, and never wants to speak to him again.

On Wednesday, the young woman, who was visibly shaken and declined to give her name and age spoke to media who had swarmed Ney’s home in western Sydney.

“I don’t want to go near him,” she said. “I feel shocked, angry, disgusted. I hate my last name.

“I just want to say sorry to the victim - she was younger than me. She could have been going out within a few hours, to go shopping with her mum, have dinner with her boyfriend. Now she can’t do that, can she?”

“All the words I’m going to say aren’t going to bring her back. I want to say I’m really sorry.”

Ney was arrested on Tuesday after a 41-year-old woman was stabbed in the back in the Sydney CBD. She is currently in a stable condition. Police later found the body of a 24-year-old woman with a laceration on her neck inside an apartment in Clarence Street.

The relative and neighbours of Ney said he and the family were not religious.

“I saw a lot of news articles saying it was about terrorism, but our family doesn’t practice Islam. Obviously, I know I am dark skinned and I look like I am from the Middle East, that’s going to be the obvious thing. But I’m not Islamic, my mum’s not Islamic, my sister isn’t Islamic, my dad is probably an atheist. We’ve got nothing to do with Islam at all.

“Using religion as an excuse it’s not correct.”

The relative, who did not want to be named for her own safety, said Ney had been “hostile” to family, and left the house last Wednesday and was taken to a mental health facility.

She said she could not say more as it was an ongoing police matter.

“In the past week, it’s obvious he’s had a steep descent into insanity,” she said. “I think he was meant to take medication ... it is clear he was mentally ill but I’m not too knowledgable because as I was saying, we’ve had an estranged relationship.

Ney is expected to be charged with murder on Wednesday, after he was arrested on Tuesday afternoon.

His mother had not been eating or drinking since, the relative said.

“She’s sick. We had to go to the doctors last night. I wish there was a way for me to make it all better for her, but I can’t. I can’t make it better for anyone else. I wish I could. I just want to say sorry to the family, sorry a million times.”

“[I don’t want] to speak to him again. I’m afraid of him.

“If this happened to a family member you knew, you wouldn’t want to go near them, would you? Something so despicable. I feel shocked, angry, disgusted. I hate my last name.”