A South Australian man has pleaded not guilty to murdering his wife more than 46 years ago.

Key points: Geoffrey Adams was prepared to plead guilty to the manslaughter of his wife

Geoffrey Adams was prepared to plead guilty to the manslaughter of his wife Colleen Adams was last seen at her home in Maitland in South Australia in 1973

Colleen Adams was last seen at her home in Maitland in South Australia in 1973 The mother of two was 24 at the time she disappeared

Geoffrey Adams, 71, appeared in the Adelaide Magistrates Court today via videolink from prison, charged with the murder of his wife Colleen Adams.

He pleaded not guilty to murder, but indicated he would admit to manslaughter.

The Director of Public Prosecutions did not accept that plea.

Mrs Adams was 24 when she was reported missing by her parents in her hometown on Maitland in December 1973.

The prosecution alleged Mrs Adams was murdered on November 26 of that year.

Mr Adams will be arraigned in the Supreme Court in April.

He will face trial at a later date.

In September 2018, SA Police found skeletal remains they believe belong to Mrs Adams.

During an earlier court appearance, a police prosecutor said Mr Adams had admitted to the crime he was charged with during a police interview.

Prosecutors told the court Mr Adams had identified the site which police excavated to find Mrs Adams' body.

When Mrs Adams went missing, she was living at the Maitland property with her husband and two young daughters.

Police digging for the remains of Colleen Adams in September 2018. ( ABC News: Simon Christie )

In 1979, police declared Mrs Adams' disappearance a major crime, with no contact made and no bank accounts accessed.

Following the arrest, Mrs Adams' daughter Kaye released a statement, saying she and her mother's family would "mourn her loss" as they found a "way to heal through this".