After going public with their search for 43-year-old Kobie Parfitt last week, on Monday morning detectives from the Missing Persons Squad announced that their investigation had escalated from being a 'suspicious' disappearance to suspected murder.

Following extensive enquiries during the last week, police now believe that the mother-of-four was last seen alive at a property on Hickman Street on April 28.

"Since that time there has been no contact and no trace whatsoever of Kobie, which is completely out of character," Detective Inspector Andrew Stamper, of the Missing Persons Squad, said.

With new information about Kobie's movements that day and the fact that her bank accounts have not been accessed since, detectives now believe she was murdered that same day.

They have spoken with many people who knew Kobie during the last week, leading to the significant development in the investigation.

"As a result of enquiries made in the Ballarat area in the last week we are sadly fairly certain that Kobie has been murdered," he said.

Kobie, who had lived in a number of locations around Ballarat prior to her disappearance - including intermittently at the Hickman Street address - had been estranged from her family at the time of her disappearance.

She was officially reported as missing a few weeks ago.

While Kobie has not been found and no arrests made, Detective Inspector Stamper said the case had gained "significant momentum" in the past week and detectives were now close to "getting to the bottom of what happened to Kobie".

Kobie had struggled with drug use but detectives have not yet determined if it could be linked with her suspected murder.

"She was involved with a group of people involved in the drug scene and criminal activity in the Ballarat area," he said. "Whether or not it [is related to what] has happened to her is why we are reaching out to the community to help us - we want more answers."

While the investigation is intensifying and detectives have a number of people of interest in their sights, they are appealing to the community for further information about who may have had a motive for murder.

Detective Inspector Stamper said he firmly believed there were people in the community who held the key to finding Kobie and solving the case and that it was only a matter of time before police found who was responsible for her disappearance.

Asked just how close police were to solving the case, Detective Inspector Stamper said:

"We are one phone call away from solving this and bringing Kobie back to her family. I am confident the information [to solve the case] is sitting somewhere in the community."

Last week, Kobie's mother, Kathy Snowball, told The Courier that her family was living a nightmare.

Detective Inspector Stamper appealed to anyone with information about "where Kobie is, what happened to her and the persons responsible" to contact Crime Stoppers.

Anyone with information is urged to contact Crime Stoppers on 1800 333 000 or to submit a confidential report at www.crimestoppersvic.com.au

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