Mr Ristevski, who was questioned by police and released without charge, was asked by a Channel 7 reporter in a press conference on Thursday if he had killed his wife.
Mr Ristevski, arm-in-arm with his wife’s visibly distressed 21-year-old daughter, Sarah, did not answer. Ms Ristevski’s aunt Patricia interjected, saying Mr Ristevski was too distressed to speak.
“That’s really not appropriate at the moment … honestly, I have to say, that is really inappropriate …This is about Karen. This is not about anything else; this is about finding Karen,” she said.
The family then left the press conference.
Before the exchange, which occurred near the banks of the Maribyrnong River where police are searching, Patricia pleaded for anyone with information to come forward.
“We’re hoping that today we will find something that will lead us to Karen,” she said.
“We have nothing, so if you have something that you know, something that you have seen, you’ve heard something, someone has spoken to you about something, anything, please, we’re asking you to help us.
“It’s not possible for someone to just disappear; it’s not Karen, Karen would not leave us.”
She described the past 15 days as a “nightmare”, and said she didn’t know who would want to cause any harm to her niece.
“If that was the case, we would already know something about that, it would be an ongoing thing,” she said.
Police and State Emergency Service volunteers searched a 60-hectare area between Canning Reserve, off Canning Street, and Afton Street, which runs along the Maribyrnong River.
The family home, which backs onto the river, sits in between.
Investigators are looking at expanding the search area on Friday.
Inspector Stephen Dennis said police had “grave concerns” for Ms Ristevski’s welfare, with her phone still off and her bank account untouched.
He said she was last seen at her home.
“We can’t say what route she may have taken from the house, so it’s still up in the air for us at this stage,” he said.
Inspector Dennis said Ms Ristevski may have had a gold-coloured Coach handbag and purse with her. Earlier, police released a photo of the items in the hope someone may come across them.
Ms Ristevski ran formal-wear shop Bella Bleu in Taylors Lakes, which she owned with her husband.
Her daughter made an emotional plea for help to find her mother last week.
Sarah told radio station 3AW she had reached out to her mother’s friends on Facebook, but to no avail.
“There are no leads at all, no sightings, nothing,” she said.
“I’ve logged on to her Facebook and contacted all of her friends. No one has seen her.”
Ms Ristevski is described as 160 centimetres tall, with a slim build and shoulder-length brown hair.
She was last seen wearing a black jacket and jeans.
Anyone who may have seen Ms Ristevski is urged to contact triple zero, while anyone with information is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential crime report to www.crimestoppersvic.com.au.