To have a loved one seemingly vanish off the face of the Earth without explanation must be one of the most traumatic experiences any family could face.
In Northern Ireland perhaps the most obvious example of such events was the mystery of the 16 people who became known as the Disappeared. Thirteen of them were eventually found, and all had been killed by republicans.
Those cases attracted worldwide publicity, but there have been other cases which are barely remembered by anyone except the person's family.
One of those was Tony Lynch, who went missing 18 years ago and whose body was only found this year in a car submerged in Lough Erne near Lisnaskea.
In a moving interview today, his son Peter tells how the family waited and waited to hear any news about their father, and had given up all hope before his body was finally found.
Over the years they had come to accept that their father was dead, but that did not ease the torment. Where was his body? Astonishingly, it was only about five miles from the family home, and Peter had often sailed in the area where the car and remains were found.
Why did he disappear? Was it the result of foul play on someone's part? The discovery of the body does not answer all the questions, but it does give a certain closure.
Now the family has a grave to visit. Peter no longer has to pretend to his children that their grandfather had simply gone away. He can begin to tell them the truth as he knows it.
In a remarkable twist of fate, the disappearance of another man in very similar circumstances came to prominence this week with the finding of a submerged vehicle in the River Bann near Bellaghy in Co Londonderry. The car is similar to one driven by Tobermore man James Patterson, who vanished in October 1991.
His disappearance was a mystery to all in the tight-knit village where he lived, and was a frequent topic of conversation. Will the car give up the secret of his death, or will his body even be found?
For his family the hope will be that they too can have a burial, a grave to visit and the knowledge at last that he has been found. It will be final confirmation that the family's decades-long fears were correct.
Their pain was never allowed to ease because there was no body to grieve over. Maybe that healing process will begin shortly.