Judge Ian Gray last year investigated the death of Lucia Amenta, a 70-year-old grandmother who was last seen outside her Fawkner home on the morning of January 19, 2008 and remained missing until her remains were discovered in a Broadmeadows creek in October 2009.

Police investigated Mrs Amenta's husband, Paolo, and their son, John, but no charges were laid.

Both men appeared as witnesses at the inquest, but Judge Gray found their evidence was "vague, unpersuasive and, to a degree, self-serving".

In his findings, released by the Coroners Court on Thursday, Judge Gray issued a non-publication order on evidence from the inquest that he considered "potentially prejudicial" in a possible criminal trial. Large sections of the findings were blacked out by court staff.

But Judge Gray stopped short of referring the case to the Director of Public Prosecutions and instead said the investigation would remain an open homicide.

He said the inquest had been unable to take the investigation any further.

"It is particularly sad that this elderly woman met her end in the way that she did, that she was not found for a lengthy period of time and that findings cannot be made about those responsible for her disappearance and death," Judge Gray said.

The inquest heard Mrs Amenta suffered neck fractures, but Judge Gray could not say whether the injuries were the cause of death or inflicted when her remains were put in the barrel.

He also said he could not determine when and where she died, or how long her remains had been in the barrel.

Judge Gray said evidence given by the Amentas' other son, Paul, was convincing and that it was unlikely he was connected to his mother's death.

Mrs Amenta was last seen outside her home by a neighbour late on the morning of January 19, 2008, while her husband was out buying groceries.

She also spoke on the telephone to a friend that morning. She was reported missing by her family that night.