A dissident republican found liable for the Omagh bombing has said that it "should never have happened".
In Monday's Irish News, Colm Murphy described the killing of 29 people, including a woman who was pregnant with twins, as "awful" and "tragic".
Michael Gallagher, whose son died in the bomb, said his words were "hollow".
"He is a lifelong republican, he is someone who has information that I'm sure could be shared with the Garda and PSNI," said Mr Gallagher.
Murphy was jailed for 14 years in 2002 for conspiracy to cause the August 1998 Real IRA bombing, but was cleared at a retrial.
In 2009 Murphy, along with four others, was found liable in a civil action brought by the families.
Speaking to BBC Radio Foyle, Mr Gallagher appealed to Murphy to share any information he has with police.
"I can't understand why Mr Murphy, and the people he associates with keep saying that Omagh was a terrible tragedy and shouldn't have happened, (but) won't come forward and support the criminal investigation," he said.
"All I can hope is that in the fullness of time that his conscious and the conscious of those who were heavily involved in Omagh will want to tell the truth about what happened."