The Bloody Sunday Trust is launching a fresh attempt to clear the name of a teenager shot dead in January 1972.
A report by Lord Saville found that Gerald Donaghey, 17, was "probably armed with nail bombs but was not a threat at the time that he was shot".
He was a member of the IRA's youth wing, but witnesses said he did not have any bombs on him.
The Donaghey family have always insisted the devices were planted by the security forces.
They said they would not rest until his name was cleared.
Conal McFeely, the chairman of the Bloody Sunday Trust, said Lord Saville's conclusion did not make sense.
"How can he ignore the fact that the people who were with Gerald Donaghey on the day didn't see nail bombs? said Mr McFeely.
"Independent civilian witnesses that came to his aid, a doctor who examined him, a British soldier, the people trying to take him to hospital, all testified that they did not see nail bombs in his possession."
Thirteen people were shot dead when soldiers opened fire on marchers during a civil rights march in Derry on 30 January, 1972.
Another man died five months later.
Thursday's move by the Bloody Sunday Trust coincides with the second anniversary of the publication of the Saville Report.