'I would have liked to': Man claiming to be stepson of missing Victoria mum denies killing her

A man claiming to be the stepson of missing Victorian mum Karen Ristevski says he was questioned by police over her disappearance.

Anthony Rickard, 32, told the Herald Sun he is the son of Mrs Ristevski's husband, Borce, and denies killing his stepmother, despite feeling anger over a family dispute.

Mrs Ristevski, 47, was last seen at her Avondale Heights home, in Melbourne's northwest, about 10am on June 29 after she went for some fresh air after a heated discussion with her husband.

Police have said they hold grave concerns for her welfare as she hasn't used her phone or accessed her bank account since.

The newspaper has not revealed the conflict Mr Rickard claims has plagued the family, but reports that the stepson, who is battling an ice addiction, has admitted he "did have a motive to hurt her".

Mr Rickard said he came to the attention of detectives after being interviewed last week over an unrelated matter.

"I said (to police), 'If you're going to say it, say it'," Mr Rickard told the Herald Sun.

"So I got them to say, 'Did you kill your stepmom?'. I said, 'I would have liked to…'."

Police have not publicly revealed any suspects in relation to Mrs Ristevski's disappearance.

There has been a wave of support on social media to find the popular dress shop owner.

With AAP