Despite growing disappointment with the results of their excavation, gardai will resume the search for the remains of Mrs Jean McConville this morning.
This follows three days of fruitless digging at Templetown Beach near Carlingford, Co Louth.
There was a suggestion yesterday that gardai would be reviewing progress this morning, but late last night this was ruled out for the moment by Supt Michael Staunton. "Obviously there will come a time when we will have to assess the situation. We haven't reached that stage yet," he said.
Mr Seamus McKendry, Mrs McConville's son-in-law, said that if gardai decided to call off the search, "me and Helen and other family members will be down here every weekend with spades."
There was no suggestion yesterday that the search was about to be called off. Gardai said they had ordered portable toilets, indicating that they were prepared for a long haul, and last night they marked out a fresh section of the car park for excavation today.
But they are becoming increasingly disillusioned with the quality of the information they received from the Commission for the Return of Victims' Remains.
This had pinpointed a specific bay in the Templetown Beach car park. It is understood that an individual brought one of the priests who was acting as an intermediary to the car park and indicated the spot where Mrs McConville was supposedly buried.
However, there was no indication of when she was buried there, and the car park was built on sand dunes 15 years after her murder.
Yesterday, Mr McKendry demanded that the IRA return to the car park and pinpoint the burial place more precisely. "The Governments, North and South, bent over backwards to accommodate those guys. They brought in legislation. But they are just not delivering. We never thought it would be easy but we did not think it would be as difficult as this," he said.
"I feel the remains of Mrs McConville are here - we are just not sure of the precise spot or whether she was reinterred here."
He and his wife, Helen, maintained their vigil by the crater yesterday, along with her sister, Agnes, and brothers, Billy and Jim. They sat in the sunshine on planks and concrete blocks inside the blue Garda screens.
The crater has been extended to the size of a swimming pool: it is 70 feet long, 20 feet wide and five feet deep. About 10 gardai were sifting through the bucketsful of sand as they were removed by the mechanical digger.
Supt Staunton, who is in charge of the Templetown excavation, said, "Your hope is reduced the longer you go on and the more you extend the search." He said he had had no direct contact with the commission and there was no independent information about where the remains lay. "I would hope that the person who indicated this site in the first place was genuine. I can accept there can be an error because of the passage of time, development etc."
The local parish priest, Father John McGrane of Cooley, came to the scene to help comfort the McConville family yesterday.
A steady trickle of local people came to the scene yesterday to invite the McConvilles to their homes for tea.