What we do know is that “nobody deserves to die like that”.

Those are her mother’s words — a woman who spoke emotionally on Tuesday about her daughter’s sad decline from a young woman who wanted everything to somebody she never spoke to who was addicted to drugs.

Ms Gatt, 40, was found dead inside the two-storey commission housing unit in January. Police say she may have been left in the bathtub since April last year while those responsible pretended she was still alive.

Her family knows she was doing drugs, but the last time they spoke to her was 18 months ago. Her mother Cheryl told reporters she had the world at her feet before drugs took hold of her life during her teenage years.

“She had a lot of big dreams which, to be honest, I knew would never really happen but she had good intentions,” she said.

Ms Gatt’s father Victor said she was “a great person” who went down a bad path and couldn’t be pulled back.

“I tried (to bring her back) and she didn’t want to do it,” her father Victor said. “I lost contact with her about 18 months ago because she didn’t want to see me. Whatever I said, she just didn’t want to do it.”

Before and after pictures show how Ms Gatt’s appearance changed dramatically during the years between aspiring teenager and drug user.

She had four kids aged between seven and 18 but dealings with police were also common. It was on January 3 this year that police went to knock on Ms Gatt’s door to issue a witness summons for a court appearance that they noticed something was wrong.

After entering the flat, they discovered Ms Gatt’s decomposing body. They say it had been there since somewhere between April 20 and April 24 last year.

The most disturbing part, according to the lead detective, is that people had “kept her alive” for the entire eight months she’d been lying in the bathtub.

Homicide Squad Detective Inspector Tim Day revealed on Tuesday that “certain actions by certain people” had led police to believe Ms Gatt was being “kept alive” for eight months after her death.

He said she was the subject of an elaborate cover-up that was beginning to unravel.

“There are certain things I need to keep to myself, but I can say and reaffirm that police believe that both the death itself was covered up and that there was an implication that she was still alive after April 20 last year,” he said.

When asked if anybody else was living in the home at the time her body was discovered, Det Insp Day said “on and off”. He said she was found “in the bathtub but certain attempts were made to conceal the fact that Sarah’s body was in the apartment”.

Fairfax reported on Tuesday that Ms Gatt’s neighbour spoke with a man believed to be her boyfriend in June last year. He reportedly told the neighbour that Ms Gatt had been admitted to a psychiatric hospital.

The neighbour, Philip Nelsson, said he was confident people were entering and exiting the house during the period after Ms Gatt went missing.

Five people were arrested shortly after Ms Gatt’s body was found. Police would not reveal who they were, but did say they included three males and two females, and that all five had been released pending further inquiries.

Det Insp Day would not be drawn on whether multiple people were involved in her death or whether somebody “was pretending to be Sarah”. He said a number of “stories” about Ms Gatt had been circulated after April 20 when police believe she was killed.

Asked whether he thought police had reached a dead end, he said “far from it”.

“We’re very optimistic in terms of the investigation. Police have a pretty good idea of what they believe has occurred.”

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