Catholic churches in the diocese of Armagh have appealed for information on the whereabouts of people murdered during the Northern Ireland conflict.
One of the various searches conducted for the Disappeared
Most of the killings under scrutiny took place over 20 years ago, but the victims' bodies are still unrecovered.
The church appeal is at the request of the Independent Commission for the Location of Victims' Remains.
The appeal has been published on church notice boards and parish bulletins in the archdiocese of Armagh.
Other dioceses will make appeals later in the week, said the BBC's Northern Ireland correspondent Denis Murray.
Nine people murdered and secretly buried by republicans during the 1970s became known as the Disappeared. The remains of four have been found, the latest in 2003.
One of the bodies was left in a graveyard on the border of Northern Ireland and the Irish Republic, our correspondent said.
Anne Morgan, whose brother Seamus Ruddy was killed by members of the Irish National Liberation Army (INLA), a republican terror group, told BBC Radio Five Live she wanted to find out exactly where his body had been buried.
"We hope that the appeal by the bishops will help jog someone's memory or someone's conscience," she said.
Jean McConville, a mother of 10, is among the Disappeared
"We hope that maybe someone who has information they may come forward.
"We feel that someone whether they're living here in Ireland, whether they're living in America, wherever they are, they will have the specific information that would help us bring closure to this."
Archbishop Sean Brady of Armagh said he was happy to support the commission's appeal. He said the plea for information was not a political act but a pastoral matter.
In a letter the commission said: "This current effort is a real opportunity to end the harrowing ordeal for the families and with this in mind, the commission appeals to anyone who has any information on any of the cases to contact them now."
The way the IRA dealt with the bodies of those they abducted and murdered was "wrong", Sinn Fein leader Gerry Adams said last year.
Sir Kenneth Bloomfield, of the Independent Commission for the Location of Victims' Remains, said there was a willingness to give information, but there were practical problems with finding bodies.
"One mustn't underestimate the difficulties in all of this because these are murders which were carried out decades ago, probably at dead of night, you know, in fairly wild country and on occasions people can give you information which to the best of their knowledge is accurate but the whole terrain has changed over these decades," he said.
The Independent Commission for the Location of Victims' Remains has provided a confidential telephone number and Post Office box address for anyone with information.
The appeal will be widened to every Catholic parish in Ireland during January.