Veronica Green, who would now be 82, was 38 when she was last seen on February 13, 1976.

Her disappearance left behind her two children aged 14 and seven at the time.

Ms Green was married and it was her husband, who has since died, who reported her missing.

Police believe Ms Green had a difficult marriage, but are not certain this was a factor in her disappearance.

A number of inquires have been investigated over the years, including several reported sightings, but none have been confirmed.

Detective Sergeant Allan Day said new information had emerged in the past 12-to-18 months about Ms Green's disappearance, leading to the decision to excavate at her former home.

"We conducted a review of the investigation and based on the older information and those bits and pieces of information that have continued to come to hand, we made the decision that we needed to search the property," Det Sgt Day told reporters on Monday.

Police are are keeping an open mind about what happened to Ms Green, including the possibility of foul play.

"We can't rule out foul play at this stage," he said.

"There are a couple of different theories on what could have occurred, but certainly, we do consider it to be suspicious and therefore we can't rule it out yet."

On the day of her disappearance, Ms Green left her Ardeer home in her grey Morris Minor and drove to the Albion railway station, where she parked and caught the train to work in Melbourne.

She never returned to pick up the vehicle.

Ms Green left all of her possessions at her home and has not been seen or heard from since.

Det Sgt Day said Ms Green's children had shown a great deal of resilience despite the difficulty of not knowing what happened to their mum.

The excavation of the backyard of the property will start on Monday under the Coroner's authority, and it is expected to take about five days.

The house has changed owners several times over 44 years and the current residents are not related or connected to Ms Green.

Australian Associated Press