Police have yet to decide whether they will take any action after they were presented with an investigator's dossier which claims to identify the killer of Jeanette and Harvey Crewe at their Pukekawa farm in 1970.
The Sunday Star-Times reported today that the dossier also names the mystery woman who allegedly fed the couple's baby.
The file was handed to assistant commissioner Peter Marshall last week.
Mr Marshall told the Sunday Star-Times he was keeping an open mind and would decide what action to take -if any - in about 10 days.
One of the enduring enigmas of New Zealand's most infamous murder mystery was who had fed the couple's 18 month old baby.
The child was found distressed in her cot at the Crewes' Pukekawa farm south of Auckland five days after the June 1970 murders and there was evidence she had been fed and changed.
The newspaper said it knew who the woman was but would not name her on legal advice.
Arthur Allan Thomas was twice wrongly convicted of the murders and spent nearly 10 years in jail until being pardoned in 1979. He declined to comment.